Navy Yard shooting

Gunman and 12 Victims Killed in Shooting at D.C. Navy Yard

WASHINGTON — At least 13 people, including one gunman, were killed, and the police were looking for other potential suspects, in a shooting Monday morning at a naval office building not far from Capitol Hill and the White House, police officials said.

One police officer was in surgery after being shot in an exchange of fire with a gunman, said Chief Cathy L. Lanier of the Metropolitan Police Department. The shootings took place at the Washington Navy Yard, in the southeast part of the city.

Senior law enforcement officials identified the gunman as Aaron Alexis, 34. He was identified through his fingerprints.

According to the Navy, Mr. Alexis enlisted as a full-time reservist in May 2007 and left the service in January 2011. He served as an aviation electrician, and the highest rank he achieved was mate third class. From February 2008 to January 2011, he was assigned to Fleet Logistics Support Squadron 46, in Fort Worth.

The Navy said Mr. Alexis had been awarded the National Defense Service Medal and the Global War on Terrorism Service Medal.

Shortly after 4 p.m., the F.B.I. released a “Seeking Information” bulletin asking for the public’s help in learning more about Mr. Alexis. The bulletin, which had two photographs of Mr. Alexis, said he was 6 feet 1 inch tall, weighed 190 pounds and was born in Queens.

Valerie Parlave, the assistant director of the Washington field office of the F.B.I., urged members of the public to look at pictures of Mr. Alexis on the F.B.I. Web site and to call with any information they might have about him.

“No piece of information is too small,” she said. “We are looking to learn everything we can about his recent movements, his contacts and his associates. We ask the public to look at the photos of the deceased shooter.”

Three weapons were found on the gunman: an AR-15 assault rifle, a shotgun and a semiautomatic pistol, an official said.

“It’s hard to carry that many guns, so there is some thinking that he may have taken some of them from security or whoever else he shot,” the official said.

One federal law enforcement official said the suspected gunman had family in New York, a mother and a sister or sisters, but had not lived there.

The official indicated that the gunman was captured on video as he entered the building before the shooting and said that it was possible that other portions of the episode were also recorded by cameras inside the building.

“We’re continuing to see if there are in fact additional shooters, but we have nothing to indicate that yet,” the official said.

As the day wore on, officials released conflicting information about the search for two possible gunmen.

Officials said one of the two gunmen they were looking for was a white man wearing a khaki Navy uniform and carrying a handgun. The other was a black man, about 50 years old, who was believed to be carrying a “long gun,” police officials said.

But officials in Washington did not move to lock down the city in light of that threat. The Metro, the city’s subway system, continued to operate normally. Out of an “abundance of caution,” Terrance W. Gainer, the Senate sergeant-at-arms, put the Senate complex into lockdown just after 3 p.m. The Senate had recessed in the early afternoon.

Meanwhile, the city’s deputy mayor for public safety wrote on Twitter just moments after Chief Lanier’s afternoon briefing that one of the men being sought had been cleared. “The white male being sought in connection to the #NavyYardShooting has been identified and is NOT a suspect,” said the post from the account of Paul A. Quander Jr., the deputy mayor.

One law enforcement official involved in the investigation said that the authorities had received few reports from witnesses of seeing gunmen who fit the descriptions that the city officials had provided. “There would have been a whole lot more damage if there had been three gunmen,” the official said.