About 2,500 gathered at Pearl Harbor today to remember those killed in the 1941 Japanese attack that launched the U.S. into World War II.

The crowd observed a moment of silence at 7:55 a.m., the minute the bombing began 72 years ago.

A vintage World War II-era airplane — a 1944 North American SNJ-5B — flew overhead to break the silence. The Hawaii Air National Guard has used its fighter jets and helicopters to perform the flyover for many years, but federal budget cuts prevented it from participating this year.

About 50 survivors returned to Pearl Harbor for the ceremony.

"I come back to be with my comrades — meet the ones who are still alive, and we’re going fast," said Delton Walling, who was assigned to the USS Pennsylvania at the time of the attack.

The Navy and National Park Service co-hosted the ceremony, which was open to the public. Their theme for the event, "Sound the Alarm," explores how Americans answered a call to duty in the wake of the attack.

The current U.S. Pacific Fleet commander, Adm. Harry B. Harris Jr., said the U.S. remembers the warning from those who survived.

"We remember Pearl Harbor, we are vigilant, and we are ready to fight tonight and win," Harris said. "Not only are we poised to respond to the first notes of the alarm bell, we are also doing everything possible to keep those alarms from sounding in the first place."

Former U.S. Sen. Max Cleland of Georgia will deliver the keynote address.

The Vietnam War veteran is currently secretary of the American Battle Monuments Commission, which is responsible for managing overseas cemeteries for fallen American troops.

Later in the day, Pearl Harbor survivors will join military and government officials in a parade through Waikiki.