(CNN) - A man "in his 60s" died on the way to a George Washington University Hospital after he was shot Monday morning at the Washington Navy Yard, a doctor said.
Three other shooting victims who were flown to MedStar Washington Hospital Center are expected to survive, hospital Chief Medical Officer Janis Orlowski told reporters at a news conference about three hours after the attack began about 8:20 a.m. Monday.
There were "individuals at the scene who will not be transported because they are deceased," Orlowski said.
A Navy spokesman told CNN there were at least 10 people wounded in the shooting at Naval Sea Systems Command headquarters.
The victims include a Washington Metropolitan police officer and a base security guard officer, said Metropolitan Police Department spokeswoman Saray Leon.
The first shooting victim evacuated from the scene was a man who suffered a gunshot to his left temple, according to Dr. Babak Sarani, chief of trauma and acute care at George Washington University Hospital.
Paramedics were unable to keep the man alive on the way to the hospital, where he was pronounced dead upon arrival, Sarani said. "Unfortunately, the injury was not survivable."
The three victims flown by helicopter to the MedStar Washington Hospital Center were "alert" and "responsive," Orlowski said. "They do have severe injuries, but we've been able to speak with all of them. They've not been able to give us any information about what happened to them."
The wounded police officer -- a male -- was in surgery for gunshot wounds that "involve bones and blood vessels of lower legs," Orlowski said.
The other victims at MedStar Washington Hospital Center were women, including one shot in the shoulder and the other with a head wound, Orlowski said. A helicopter plucked one of the wounded women from a roof and carried her to the hospital, she said.
"Their chances of survival are very good," she said.
Doctors have been told to expect more victims, she said.