HOLLYWOOD, Fla. -- A police dog was killed when his handler left him locked in a hot police cruiser in south Florida.

Astro was part of the Broward County canine unit.

Wednesday, the dog's deputy handler said he left Astro locked in the car with the engine and the air conditioning on, but when he returned to the car it was overheating and smoking.

Rescue workers did everything they could to save Astro, but it was too late.

"I can tell you this has been very devastating to him. This is their family member," said Veda Coleman-Wright, Broward County Sheriff's Office.

Deputies said the cruiser has an alarm that sounds and drops the windows if something happens to the car while the canine is inside. Investigators were trying to figure out why the alarm system malfunctioned.