Arizona police are investigating a deadly hazmat situation at a truck wash in Avondale.

The incident occurred on the afternoon of Sunday, August 29, at Danny’s Truck Wash, located off of I-10.

“This is a commercial truck wash and the two victims were located inside the container of a tractor trailer semi truck,” Avondale Fire & Medical Deputy Chief Ben Avitia told Fox 10.

Firefighters in hazmat gear were able to recover the two victims.

The two men were taken to the hospital in critical condition from exposure to chemicals in the tanker. Both men later passed away.

Four firefighters who responded to the scene suffered from heat-related illnesses and were transported to the hospital.

The incident is under investigation by the Avondale Police Department.