WASHINGTON - President Barack Obama is mourning what he called "yet another mass shooting" in the United States that he says took the life of American patriots.
Obama promised to make sure, quote, "whoever carried out this cowardly act is held responsible."
He said several people were shot Monday morning at the Washington Navy Yard about 3 1/2 miles from the White House, and some were killed.
He said the victims were "courageous Americans" who knew about the risks of serving overseas, but wouldn't have expected such "unimaginable violence" at home.
The White House says the president has been receiving frequent briefings about the unfolding situation by senior aides.
Biden: May have been more than 1 Navy Yard shooter
Vice President Joe Biden says he's been told there may be more than one shooter in a shooting at the Washington Navy Yard.
Biden says the situation is still unfolding, but it's clear a tragedy has occurred. He says he and the White House are praying for the safety of military and police personnel who are trying to bring the situation under control.
Biden says he's been briefed by his national security staff as he's traveling Monday to South Carolina and Georgia.
Officials say six people were killed and at least four were wounded on Monday morning, including a law enforcement officer.
Biden spoke at a port in Charleston during an event highlighting the need to invest in the nation's infrastructure.