A shooter opened fire in a classroom building at the Naval Air Station in Pensacola on Friday morning in an attack that left four people dead, including the assailant, and multiple people wounded.

The shooting — the second at a U.S. Navy base this week — prompted a massive law enforcement response and a lockdown at the base.

Eleven people were shot all together, including two sheriff’s deputies who were the first to respond, one of whom killed the shooter, Escambia County Sheriff David Morgan said. One of the deputies was shot in the arm and the other in the knee, and both were expected to recover, he said.

Commanding base officer Capt. Timothy Kinsella Jr. would not say if the shooter belonged to the military and said he did not want to speculate on whether the shooting was terrorism-related.

Alex McGinley, a tattoo artist who works near the base, said he was alerted to the shooting by one of his clients, most of whom are military personnel. He said none of his clients was among those shot.

“What kind of things go through a person’s mind to a level that makes them do something like that?” McGinley asked.

The base remained closed until further notice and those still on base would remain there until it was safe to evacuate, Kinsella said.

NAS Pensacola employs more than 16,000 military and 7,400 civilian personnel, according to its website. One of the Navy’s most historic and storied bases, it sprawls along the waterfront southwest of downtown Pensacola and dominates the economy of the surrounding area.

Part of the Pensacola base resembles a college campus, with buildings where 60,000 members of the Navy, Marines, Air Force and Coast Guard receive training each year in multiple fields of aviation.

The base is home is home to the Blue Angels flight demonstration team, and includes the National Naval Aviation Museum, a popular regional tourist attraction.

The shooting is the second at a U.S. naval base this week. A sailor whose submarine was docked at Pearl Harbor, Hawaii, opened fire on three civilian employees Wednesday, killing two before taking his own life.