Five people were gunned down on Thursday, November 12, in a trendy Washington, D.C., neighborhood within walking distance of the White House.
A swarm of officers responded to a nearby apartment building where a suspect was believed to be barricaded.
At least one person was found deceased in a pool of blood after being fatally injured at the gym, a witness said.
The incident took place in Logan Circle, about a mile north of the White House.
Schools were placed on lockdown as law enforcement SWAT teams and other officers had their guns drawn on the roof of an apartment building or on the ground below.
Authorities believe the suspect fired at at least one person inside the gym before going outside and firing again, according to a law enforcement official who was not authorized to publicly discuss the investigation and spoke to The Associated Press on the condition of anonymity.
Law enforcement agents believe the suspect fired at another person in a parking garage elevator and then barricaded himself on the seventh floor of the building, the official said.
Witness James Spellman, who was at the gym, said there were about 50 people there around 8 a.m. when the shooting began.
“Within seconds there was a man who fell to the ground, and a pool of blood came out,” he said. “One gym member rushed to help him. He had been shot in the neck.”
Spellman said he and others dashed out of the gym. He said he heard about two shots fired in the gym and about five or six fired outside.
Another witness, Ryan Dubicki, said he was in his nearby apartment around the same time when he “heard about five bangs.”
“They were really spread out so I thought it was construction,” he said. A short time later “there were cops everywhere.”
The federal Bureau of Alcohol, Tobacco, Firearms and Explosives said it sent agents to the scene to help. And the FBI said its Washington field office was helping local police with the investigation.