Navy Yard Shooting Witness: He aimed his gun at us, Navy Yard shooting: Multiple deaths and injuries

At least one gunman opened fire at the U.S. Navy Yard in Washington, D.C, this morning, killing several people and injuring others, authorities said.

One hospital received three shooting victims -- a man and two women. The man is a D.C. police officer, said Janis Orlowski of Medstar Washington Hospital Center. She said all three victims were alert and speaking. She said their chances of survival were "very good."

Orlowski said it was a "very fluid situation" and more shooting victims would be coming to Medstar.

She said there were other shooting victims at the Navy Yard who would not be transported to hospitals because they are "deceased." She did not have a number of the fatalities.

Orlowski said the weapon or weapons used in the shooting "had to be semi-automatic," based on descriptions by the three people admitted at Medstar. She said they described rapid gunfire at the Navy Yard.

A D.C. police spokesman said five people had been shot at the Naval Sea Systems Command headquarters, including a D.C. police officer and one other law enforcement officer. Related Live feed: Latest from Twitter Raw video: Air lift at scene of Navy Yard shooting Video: Airlift at Navy Yard Raw video: Scene of D.C. Navy Yard shooting Raw video: Scene of Navy Yard shooting Shots fired at Navy Yard in Washington D.C. [Video] Video: Shooting at Navy Yard Watch live: Washington Navy Yard shooting Navy Yard