A U.S. counterterrorism operation in January accidentally killed two male hostages - an American aid worker and an Italian - held by al-Qaida on the Afghan-Pakistan border, the White House said.
A U.S. official told VOA the hostages were killed during airstrikes by unmanned drone aircraft on January 14.
President Barack Obama on Thursday personally apologized for the incident. An official statement said there was "tremendous sorrow" over the death of the two hostages: American Warren Weinstein and Italian Giovanni Lo Porto. Both had been working on aid projects in Pakistan.
"As president and commander-in-chief, I take full responsibility for all our counterterrorism operations, including the ones that inadvertently took the lives of Warren and Giovanni," Obama said at the White House. "I profoundly regret what happened."
Intelligence that led to strike
The president told reporters, "Based on the intelligence that we obtained at the time, including hundreds of hours of surveillance, we believed this was an al-Qaida compound, that no civilians were present and that capturing these terrorists was not possible."
A U.S. official told VOA that they "had near clarity” on what was targeted on January 14 and 19, after intelligence showed "a pattern of life" at the compound and "assessed with a very high level of confidence the compounds hosted only al-Qaida members."
“These hostages had been hidden and well-concealed," the official said.
The White House says the president did not personally sign off on the two specific strikes in which the hostages were killed.
Pres Obama offers condolences following unintentional killings of US, Italian hostages; takes full responsibility for all ops #voaalert— Luis Ramirez (@LuisVOA) April 23, 2015
"As a husband and as a father, I cannot begin to imagine the anguish that the Weinstein and Lo Porto families are enduring today," Obama said, with a deep sigh, saying he has ordered a full review.
"I realize there are no words that can ever equal their loss,'' he said.
Obama said he declassified some details of the operation so that the families could know what happened.
Warren Weinstein's wife, Elaine, said in a statement on behalf of the family, "On behalf of myself, our two daughters, our son-in-law and two grandchildren, we are devastated by this news and the knowledge that my husband will never safely return home.
"We were so hopeful that those in the U.S. and Pakistani governments with the power to take action and secure his release would have done everything possible to do so and there are no words to do justice to the disappointment and heartbreak we are going through.
"We do not yet fully understand all of the facts surrounding Warren's death but we do understand that the U.S. government will be conducting an independent investigation of the circumstances. We look forward to the results of that investigation.
"But those who took Warren captive over three years ago bear ultimate responsibility. I can assure you that he would still be alive and well if they had allowed him to return home after his time abroad working to help the people of Pakistan," she said.
U.S. lawmakers also expressed condolences Thursday to the victims' families.
U.S. officials say Ahmed Farouq, an American whom the White House says was an al-Qaida leader, was killed in the same operation. U.S. officials have also concluded that Adam Gadahn, an American who had served as a spokesman for the terror network, was killed in a separate American operation on January 19.
"While both Farouq and Gadahn were al-Qaida members, neither was specifically targeted," the White House statement said.
An official told VOA the U.S. was not aware the American al-Qaida members were at the strike locations and that it wasn't until April, following an intelligence unit post-strike assessment that began on January 21, that the government had “high confidence” that the Americans indeed had been killed.
Al-Qaida in the Indian Subcontinent (AQIS) acknowledged in a message sent to reporters including VOA's Ayaz Gul that Farouq had been killed in a U.S. strike. The AQIS spokesman said Farouq was a resident of Islamabad and had received “Sharia” education at the city’s International Islamic University.
More about hostages
Weinstein, who was from a suburb of Washington, was a business-development expert working in Pakistan on a contract with the U.S. Agency for International Development. He had been in Pakistan for close to seven years when the gunmen stormed his residence and took him away in 2011.
Lo Porto was kidnapped in January 2012 while working in Pakistan for the German aid group Welthungerhilfe.
The White House said Obama believes it is important to provide the American people with as much information as possible about "our counterterrorism operations, particularly when they take the lives of fellow citizens."
The White House said that while it believes the operations were lawful, the U.S. is conducting an independent review to understand what happened.
Jeff Seldin contributed to this report from the Pentagon, Luis Ramirez contributed to this report from the White House, Ayesha Tanzeem contributed to this report from Islamabad.