Maryland State Police are investigating an air crash between a helicopter and a plane that has left three people dead and two injured, CBS Baltimore reported Thursday. The collision occurred near the small Frederick Municipal Airport, which is northwest of Washington, D.C., at around 3:40 p.m., Capt. Kevin Fox of Frederick County Fire and Rescue said, according to the Associated Press.

The injured were taken to Meritus Medical Center's trauma center in Hagerstown, Maryland. The extent of their injuries is unknown.

The R44 helicopter, which was in the middle of a training exercise, subsequently crashed in an industrial park, the AP wrote. It’s unknown whether one or two people were in the helicopter at the time of the crash. The R44 was heavily damaged.

The Cirrus SR22 plane crashed 100 yards away in some trees. It was reportedly heading to Frederick from Cleveland, Tennessee.

Air traffic resumed at Frederick Municipal Airport around 5:30 p.m. The airport, which has two runways, opened in 1948.

The National Transportation Safety Board and the FAA will investigate the accident, the AP said.

This is a developing story….

Follow me on Twitter @mariamzzarella