An explosion Tuesday at a tanker truck company in Corona killed a 50-year-old man and sent a second man to the hospital, authorities say.

The identity of the dead man has not been released because notification to relatives has not been made.

The second man is hospitalized in critical condition, authorities said.

Authorities are unsure about the cause of the explosion, said Sgt. Kim Velasco, spokeswoman for the Corona Police Department.

The blast was called in about 1:50 p.m. at National Distribution Services in the 300 block of North Grant Avenue. Moments before the explosion, six to 10 employees were welding a truck, Velasco said.

Witnesses described the explosion's sound to Corona Fire Department officials as "two cars colliding."

Velasco said the business was evacuated.

The explosion was contained to National Distribution Services, which is in a residential area. Hazmat crews were called to the scene but no nearby homes were evacuated.

Because the incident is not a homicide, California Occupational Safety and Health Administration will oversee the investigation, which will include what caused the explosion and if there were any workplace safety violations, said Cal/OSHA spokesman Greg Siggins.

The investigation could take up to six months before determining what caused the fatal blast.