Gunman, 12 victims killed in Washington Navy Yard shooting

The police are still looking for a motive and additional suspects

At least 13 people, including a gunman, were killed and the police were looking for another suspect, in an audacious mass shooting at the high-security Washington Navy Yard located at a short distance from the White House.

"We now have a total of 13 fatalities, including the shooter," the Washington DC Mayor Vincent Gray told reporters at a news conference yesterday.

"We don't know what the motive is at this stage. We'll continue to seek information about what the motive is, but we don't have any reason at this stage to suspect terrorism, but certainly it has not been ruled out," he said.

One of the shooter who died in the brazen incident was identified by the police as Aaron Alexis, a 34-year old military contractor from Fort Worth, Texas. Police officials said Alexis managed to get inside the building by using someone else's identification card.

However, it is still not clear what was motive of the shooter and how many other people accompanied him or he was alone. Initially police said they were looking for two more suspects.

"Earlier today we talked about the possibility of there being two other suspects. One of those has been ruled out. That gentleman has been identified and is no longer a suspect," Gray said.

As a matter of precaution, the Senate building was locked down for several hours yesterday only to be partially lifted later in the evening.

Gray said yet another person is being looked out at.

"There is still yet another person who was identified earlier. That was a person in the video who was wearing a drab olive uniform, around 50 years of age, around 5'10", African-American man, and we are continuing to look for him to determine what if any involvement he may have had," he said.

The Washington Metropolitan Chief of Police, Cathy Lanier, asked residents, communities and businesses in the immediate area to shelter in place and avoid the areas mentioned until they finish their work.

FBI official Valerie Parlave asked public to share any information they might have about the suspect shooter.

"This remains a very active investigation. We will continue to run down every lead and we will continue to work together on this investigation with our law enforcement partners," he said.