UPDATE (5:48PM): According to Kern County Fire officials, those four firefighters have been released from the hospital. Officials say the heat-related injuries were due to crews fighting multiple units and the high temperatures. 

KCFD and the Bakersfield Fire Department take a proactive approach in safety training for their firefighter crews.

The Kern County Fire Department said four firefighters were injured while responding to calls Sunday. 

KCFD crews responded to three structure fires in the southeast side of the county Sunday. Four firefighters were taken to local hospitals with heat-related injuries. One firefighter was admitted to the hospital and the other three are being evaluated.

KCFD has not released the names of those firefighters.