President Barack Obama on Wednesday condemned the attack on the U.S. consulate in Benghazi, Libya that killed four Americans, including Ambassador Chris Stevens on Tuesday. Obama also responded to criticism from Republican presidential candidate Mitt Romney.
The White House said Obama spoke with the families of Ambassador Stevens and Sean Smith, another embassy employee who was killed in Benghazi.
In the White House Rose Garden with Secretary of State Hillary Clinton by his side, Obama said he ordered steps to enhance security for U.S. diplomats and personnel around the world.
The United States, he said, will not rest until those responsible for the killings are brought to justice.
"We are working with the government of Libya to secure our diplomats, and I have also directed my administration to increase our security at diplomatic posts around the world. And make no mistake, we will work with the Libyan government to bring to justice the killers who attacked our people," Obama said.
Watch a related report by VOA's Scott Stearns
Ambassador Stevens and the three other Americans were killed when a mob, angered by an amateur film that mocks Islam's Prophet Muhammad, stormed the U.S. consulate in Libya.
In Egypt, protesters scaled the walls of the U.S. embassy in Cairo on Tuesday, destroying an American flag and replacing it with an Islamic banner -- also in response to the film.
Stevens' death was the first of an American ambassador abroad in more than 20 years. The State Department identified Foreign Service Information Management Officer, Sean Smith, as one of the others killed.
VIDEO: Hillary Clinton on Libya Attacks 9/12/12
Secretary Clinton spoke earlier at the State Department.
"This is an attack that should shock the conscience of people of all faiths around the world. We condemn in the strongest terms this senseless act of violence and we send our prayers to the families, friends and colleagues of those we have lost," she said. "This was an attack by a small and savage group, not the people or government of Libya."
Q&A Paul Westpheling talks to VOA's Elizabeth Arrott and Scott Stearns on events in Libya
U.S. pledges justice
Clinton said the United States will continue to work with the government and people of Libya, but pledged to bring those responsible for the deaths to justice.
Clinton said the relationship between the U.S. and Libya will not be "another casualty" of the attack, and the U.S. will not turn its back on the Libyan transition to a free and democratic nation.
The president of Libya's national assembly, Mohammed Magarief, apologized Wednesday "to the United States, the people and to the whole world for what happened."
Libya's Deputy Interior Minister Wanis al-Sharif told reporters that an armed group attacked the premises in an "almost suicidal" mission. He said the U.S. consulate was at "fault" for not taking adequate precautions. But further details of the incident were unclear.
Earlier reports said several dozen gunmen from the Islamist group Ansar al Sharia attacked the U.S. consulate with automatic rifles and rocket-propelled grenades, then set it on fire. The Associated Press reported that Stevens and his colleagues were killed when he went to the consulate to evacuate staff.
In Egypt, protesters scaled the walls of the U.S. embassy in Cairo, tore up an American flag and replaced it with an Islamic banner. The demonstrators there — mainly ultraconservative Islamists — continued their protest action through the early hours of Wednesday.
The protests coincided with the 11th anniversary of the September 11 terrorist attacks in the United States.
In US, attack resonates on campaign trail
The Libya attack and an assault on the U.S. embassy in Cairo have entered the U.S. presidential contest between President Obama and Republican Mitt Romney.
Romney says a statement from the U.S. embassy in Cairo appeared to sympathize with attacks protesting the film.
At a news conference, Romney criticized the Obama administration.
"They clearly sent mixed messages to the world, and the statement that came from the administration — and the embassy is the administration — was a statement which is akin to apology, and I think was a severe miscalculation," he said.
The Obama campaign issued a statement saying it was shocked that Romney would choose a time when the United States is confronting the tragic death of one of its diplomats "to launch a political attack."
In a CBS News interview late Wednesday, President Obama defended the statement issued by the U.S. embassy in Cairo, saying it was intended to calm a situation that potentially placed Americans in danger. He criticized what he called Romney's "tendency to shoot first and aim later." As president, Obama added, he has learned the importance of making sure statements are thought through and backed up by facts.
President Obama said that the United States "rejects all efforts to denigrate the religious beliefs of others," and said "there is absolutely no justification" for senseless violence."
President Obama visited employees at the State Department to express his solidarity with them following the deaths of the American personnel in Libya.
The White House has not commented on media reports quoting unidentified officials as saying the attack in Libya was planned and not spontaneous.
The White House says President Obama is monitoring the situation in Libya and in Egypt as he begins a two-day campaign trip. The president ordered all U.S. flags lowered to half-staff in memory of those killed in Benghazi.
Clips from the movie in English and Arabic recently posted on YouTube show the Prophet Muhammad as a child of undetermined parentage and portray him as a buffoon who advocates child abuse and extramarital sex, among other overtly insulting claims.
The Associated Press reported that alleged filmmaker, Sam Bacile, is a California-based real estate developer who went into hiding Tuesday. The AP quotes him as describing Islam as a "cancer," and said he intended his film to be a provocative political statement condemning the religion.
The video gained international attention with its promotion by controversial Florida-based Christian Pastor Terry Jones, who said Tuesday the film was not designed to attack Muslims but to show the "destructive ideology of Islam."
Jones triggered deadly riots in Afghanistan in 2010 and 2011 by threatening to set fire to copies of the Quran and then burning one in his church.
Tuesday's twin assaults were the first on U.S. diplomatic facilities in either country, at a time when both Libya and Egypt are struggling to overcome the turmoil following the ouster of their longtime leaders, Moammar Gadhafi and Hosni Mubarak in uprisings last year.
It is not clear if the two incidents were coordinated.
Benghazi, a stronghold of Islamist extremists and cradle of the revolution that saw strongman Gadhafi captured and killed last year, has seen a wave of violence in recent months, including attacks on Western targets, bombings of military buildings and the killings of army and security officers.
Egypt's Al Ahram newspaper reported that a spokesman for the Muslim Brotherhood, the main Egyptian Islamist group, urged the U.S. government to prosecute the "madmen" behind the video.
Yemeni protestors break a door of the U.S. Embassy during a protest about a film ridiculing Islam's Prophet Mohammed, Sana'a, Yemen, September 13, 2012.
Yemenis protest in front of the U.S. Embassy during a protest about a film ridiculing Islam's Prophet Mohammed, Sana'a, September 13, 2012.
Egyptian protesters burn tires as they clash with riot police outside the U.S. embassy in Cairo, Egypt, September 13, 2012.
An Egyptian protester throws back a tear gas canister toward riot police outside the U.S. embassy in Cairo, September 13, 2012.
A policeman stands in front of a police car set on fire by protesters in front of the U.S. embassy in Cairo, Egypt, during clashes between protesters and police, September 13, 2012.
White House staff are pictured after they lowered the U.S. flag to half staff on the roof of the White House in Washington, September 12, 2012, following the death of U.S. Ambassador to Libya, Chris Stevens.
President Barack Obama delivers a statement with Secretary of State Hillary Clinton from the Rose Garden of the White House in Washington, September 12, 2012
A burnt car is parked at the U.S. consulate, which was attacked and set on fire by gunmen, in Benghazi, Libya, September 12, 2012.
An exterior view of the U.S. consulate, which was attacked and set on fire by gunmen yesterday, in Benghazi September 12, 2012.
An interior view of the damage at the U.S. consulate, which was attacked and set on fire by gunmen yesterday, in Benghazi, Libya, September 12, 2012.
Christopher Stevens, the U.S. ambassador to Libya, was killed along with three of his staff on September 11, 2012 during a demonstration at the U.S. consulate in Benghazi. This photo was taken at his home in Tripoli, June 28, 2012.
A vehicle sits smoldering in flames after being set on fire inside the US consulate compound in Benghazi late on September 11, 2012.
An armed man waves his rifle as buildings and cars are engulfed in flames after being set on fire inside the U.S. consulate compound in Benghazi, Libya, late on September 11, 2012.
U.S. Consulate in Benghazi in flames during protest, September 11, 2012
Also Tuesday, Egypt's prestigious Al-Azhar mosque condemned a symbolic "trial" of the Prophet Muhammad organized by a U.S. group, including Jones.
At least 2,000 unarmed demonstrators had gathered Tuesday outside the embassy in the Egyptian capital, including Salafist Muslims and soccer fans who were involved in the political protests that brought down the former government.
By nightfall, a group of protesters had breached the wall, destroying the U.S. flag and replacing it with an Islamic banner. An embassy official said no guns were drawn and no shots were fired during the incident. He said all the employees on the compound were safe.
VOA's Middle East Voices is tracking worldwide reaction to events in Libya here
VOA correspondents Mark Snowiss and Carla Babb contributed to this report.