At least 12 fatalities in U.S. Navy Yard shooting

Washington Metropolitan Police Chief Cathy Lanier confirmed Monday that there were at least 12 fatalities in a mass shooting earlier in the day at the U.S. Navy Yard in Washington, D.C..

One suspect was pronounced dead in the Navy Yard shooting, and the police were searching for two other potential suspects at large, said local police authorities.

One suspected shooter was killed on site, and the police believed two other possible gunmen -- a white man and a black man, both in military-style clothing -- were still on the loose, said Lanier, chief of Washington Metropolitan Police Department, in a televised briefing held earlier.

She also said one police officer was shot in engagement with the suspects of the shooting.

This is believed to be an isolated incident so far, said District of Columbia Mayor Vincent Gray at the same televised briefing. He said motive and the number of the shooters were not clear.

Janis Orlowski, chief medical officer of Washington Hospital Center, said the hospital has received three people wounded in the shooting, including a D.C. Washington Metropolitan police officer.

The incident happened at 8:20 a.m. EDT (1320 GMT) when at least a shooter opened fires inside a building at the Washington Navy Yard that serves as the Naval Sea Systems Command Headquarters, the U.S. Navy said on Twitter.

Speaking before a televised speech on the fifth anniversary of the financial crisis at the White House, U.S. President Barack Obama condemned Monday's shooting and sent his thoughts and prayers to the victims and their families.

"We still don't know all the facts. But we do know that several people have been shot, and some have been killed. So we are confronting yet another mass shooting," said Obama, vowing to investigate the incident thoroughly and hold those behind the tragedy responsible.