Officials said Monday there are no indications yet that the alleged shooter in the Navy Yard attack is connected to terrorism, though his name is being run through various databases.
Aaron Alexis, 34, was identified late Monday as the shooter. Police say 13 people, including the shooter, were killed.
Fox News is told that Alexis' name is being run through various watch lists, including databases maintained by the Department of Homeland Security and National Counterterrorism Center.
A source familiar with the checks said "there is nothing yet to indicate terrorism."
Fox News is told Alexis is an American citizen. He was a Navy reservist who served between 2007 and 2011.
In a press conference Monday afternoon, D.C. Mayor Vincent Gray said officials still don't know the motive.
"We don't have any reason at this stage to suspect terrorism, but certainly it has not been ruled out," he said.
Fox News' Catherine Herridge contributed to this report.