Washington: At least 12 people, including an Indian-American, were killed by a lone gunman in an audacious mass shooting at the high-security Washington Navy Yard located at a short distance from the White House.In all 12 people – mostly military contractors – were killed when the gunman, himself a defence contractor, went on a shooting rampage inside the Washington Navy Yard yesterday."We now have a total of 13 fatalities, including the shooter," the Washington DC Mayor, Vincent Gray, told reporters at a news conference.The Washington Metropolitan Police yesterday released the names of seven of those who were killed in the shootout, with one of them being 61-year-old Indian-American Vishnu Pandit. The other six identified were Michael Arnold, 59; Sylvia Frasier, 53; Kathy Gaarde, 62; John Roger Johnson, 73; Frank Kohler, 50; and Kenneth Bernard Proctor, 46. No other details were immediately known about Pandit, except that he was a defence contractor."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," Gray said.The shooter, who died in the brazen incident, was identified as 34-year-old military contractor Aaron Alexis. According to officials, Alexis left Texas about a year ago.He is believed to have entered the Navy Yard with a valid badge and had been in the Washington region for about four months. He worked as an hourly employee with a defence contractor.According to biographical data provided by the Navy, Alexis had been in the Navy as a full-time reservist from May 2007 to January 2011, and left as a petty officer third class. President Barack Obama condemned the shooting at Washington's Navy Yard as a "cowardly act".Later, Obama issued a proclamation in the honour of those who died in the shooting and ordered that the national flag be flown at half-mast.He also cancelled a musical evening scheduled at the White House. Obama, who personally monitored the developments, called FBI director James Comey to get an update on the incident. Initially police said they were looking for two more suspects. "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.