FBI agents and heavily armed agents from the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives have been seen outside the Northside Hospital Midtown medical office building, where an active shooter situation is unfolding Wednesday.

One officer with a “negotiator” patch was seen entering the medical center. A registered nurse from the Fulton County Police Department was also seen there, wearing a helmet and full SWAT gear.

MARTA police, the Georgia State Patrol, Fulton County marshals and South Fulton police are also at the scene, as well as several SWAT units. Atlanta police remain the lead agency at this point, according to the FBI, which has offered assistance as necessary.

Atlanta police have confirmed five people were shot, and one person was killed. The shooter remains at large.

Caden Pike, 24, of Douglasville, was pumping concrete at a high rise under construction two blocks from the medical center when he saw about five fire trucks, five or six ambulances, and “I cant even count how many police cars came by,” he said. “It was crazy.”

While he is aware of the shelter in place order, he and his crew are stuck on West Peachtree Street, which is closed to traffic.

“We really can’t go anywhere, ‘cause we are blocked in and stuck,” Pike said.