NEW YORK — Americans gathered in jubilant crowds to cheer, sing and applaud early Monday after the president announced that Osama bin Laden was killed, including hundreds gathered at ground zero where the twin towers once stood in Lower Manhattan.

Many there waved American flags or took pictures. The group broke into spontaneous cheers and song, including a rendition of Lee Greenwood’s “I’m Proud to be an American.”

Farther uptown in Times Square, dozens stood together on the clear spring night, making calls and snapping photos. An FDNY SUV drove by and flashed its lights and sounded its siren, and the crowd broke into applause. A man held an American flag and others sang “The Star-Spangled Banner.”

And in Washington, D.C., a large group gathered in front of the White House to celebrate, chanting “USA! USA!” and waving American flags. The throng had filled the street in front and was spilling into Lafayette Park.

Will Ditto, 25, a legislative aide, said he was getting ready to go to bed Sunday night when his mom called him with the news. He decided to leave his home on Capitol Hill and join the crowd. As he rode the subway to the White House, he told fellow passengers the news.

“It’s huge,” he said. “It’s a great day to be an American.”

George Washington University student Alex Washofsky, 20, and his roommate Dan Fallon, 20, joined the crowd.

“George Bush said, ‘Bring him to justice, dead or alive,’ and we did it,” said Washofsky, a junior and a member of the Navy Reserve Officer Training Corps.

The crowd began gathering before President Barack Obama addressed the nation at about 11:30 p.m. Sunday. By midnight, people had filled a street directly in front of the White House and the celebration was spilling over into Lafayette Park to the north.

Some people sprinted up on foot to join the crowd. Others arrived on bicycles, and some people brought dogs.

American flags of all sizes were being held aloft, worn draped over the shoulders or gripped by many hands for a group wave. Some people climbed trees and lampposts to better display the flags they carried. Others without flags simply pumped their fists in the air.

The impromptu street party took on aspects of a pep rally, at times. Some people offered up the “hey, hey, good-bye” sing-song chant more typically used to send defeated teams off to their locker rooms. And Parth Chauhan, 20, a sophomore at George Washington University, trumpeted a vuvuzela.

In Dearborn, Mich., a, heavily Middle Eastern suburb that’s home to one of the nation’s largest Arab and Muslim communities, a small crowd gathered outside City Hall, chanting “USA” and waving American flags.

Across town, some honked their car horns as they drove along the main street where most of the Arab-American restaurants and shops are located.

At the Arabica Cafi, the big screen TVs that normally show sports were all turned to news about bin Laden.

Cafi manager Mohamed Kobeissi says it’s finally justice for those victims.

In Philadelphia, at a game between the New York Mets and Philadelphia Phillies, chants of “USA! USA!” began in the top of the ninth inning at Citizens Bank Park. Fans could be seen all over the stadium checking their phones and sharing the news.