Two crew members were killed when a medical helicopter crashed in Shelby County, Alabama, authorities said Sunday.

The Life Saver helicopter had been called to transport a hiker who had been experiencing chest pains and breathing problems, Shelby County Sheriff’s Office chief deputy Clay Hammac said Sunday night. The helicopter crashed a little before 5:30 p.m. local time. 

“There were three crew members on board the aircraft at the time of the crash,” Hammac said. “Tragically, I can say now that we can confirm the fatality of two.”

The hiker was not on the helicopter when it crashed, according to Air Method, the company that operated the aircraft. One crew member was pronounced dead at the scene and a second died after being taken to the hospital, Air Method said. The third crew member was also transported to the hospital and was in critical condition as of Sunday night, the company said.

The hiker was taken to a local hospital separate from the helicopter crew. The hiker’s condition was not immediately known.

None of the victims were immediately identified.

The National Transportation Safety Board will investigate the crash.

“Our hearts go out to the families of these two members of the flight crew that have passed away,” Chelsea Mayor Tony Picklesimer said Sunday night. “And my heartfelt thanks to, my heroes, that Chelsea Fire and Rescue that responded, and to the deputies that responded. And please remember these families that will be left behind and that have had to deal with this tragic event.”

The road near where the crash happened will remain closed overnight and “will likely remain closed during tomorrow’s morning commute,” the SCSO’s office said on Facebook.