At the Capitol, police armed with military-style assault rifles were posted at the intersection of Constitution and Delaware avenues to intercept traffic headed to the Senate side of the complex.
The U.S. Capitol was on high alert, but did not go into lockdown inside the building.
U.S. Capitol Police say they are assisting authorities at the Washington Navy Yard.
Law enforcement sources said the Secret Service is also on high alert and that with two possible shooters at large, all protectees would be sheltered in place or moved to more secure settings.
- With Jeffrey Anderson