Law enforcement officials across the United States are boosting security for Independence Day events, after security agencies warned about potential terrorist threats timed to the July 4 holiday.
The Department of Homeland Security and the Federal Bureau of Investigation issued an alert earlier this week, calling for local authorities and the public to remain vigilant for possible threats following recent calls for violence by the Islamic State group during Ramadan.
Terror attacks last week in Tunisia, Kuwait and France, in which dozens of civilians were killed, prompted U.S. Homeland Security Secretary Jeh Johnson to issue a statement calling for increased vigilance over the patriotic holiday in the United States.
The Islamic State group claimed responsibility for the Tunisia and Kuwait attacks.
Law enforcement officials in the United States are on high alert for possible terrorist attacks on Saturday. They are particularly concerned about "soft" targets following last weeks attack at a Tunisian beach that killed 38 people.
"We've prepared for worst-case scenarios, and we have contingencies in place should they occur," a U.S. Park Police officer said on CNN.
Authorities are advising people to be aware of their surroundings and to notify police if they see something they find suspicious.
On Thursday, a false report of a gunman at the U.S. Navy Yard in southeast Washington, D.C., sparked a massive police response, an indication of heightened security concerns in the nation's capital.
Two years ago, a government contractor at the Navy Yard shot and killed 12 people before being killed by police in a shootout.
District of Columbia Police Chief Cathy Lanier briefs reporters at the Washington Navy Yard, Sept. 16, 2013.
Washington police Chief Cathy Lanier, speaking at a news conference Thursday, said, "We take every event here in Washington seriously and our caution remains especially high for all special events and it will continue for the 4th of July."
Hundreds of thousands of tourists are expected on the National Mall for Saturday's annual "A Capitol Fourth" celebration, which is capped by an enormous fireworks shows.
Extra law enforcement will be on duty for the weekend, and extra fencing and security checkpoints have been put in place throughout the Mall.
On Friday, New York Governor Andrew Cuomo ordered heightened security measures across the state over the long holiday weekend.
"We are keenly aware that New York State remains a top target for terrorists," Cuomo said in a statement.
New York measures
New York City, which has the nation's largest municipal police force, assigned about 7,000 officers and nearly all its counterterrorism personnel to handle security around Independence Day events.
State Department spokesman John Kirby said the department reminded posts several weeks ago to review their security procedures.
"The reminder issued by the State Department is routine, done before all major holidays, and is not indicative of any specific security threat," Kirby said in a statement Friday.
Meanwhile, the Federal Aviation Administration reminded Americans earlier this week the Washington metropolitan area will be a "no drone zone."
"The airspace around Washington, D.C., is more restricted than in any other part of the country. Rules put in place after the 9/11 attacks establish 'national defense airspace' over the area," it said.
Mary Alice Salinas contributed to this report.