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ST. LOUIS, MO (KTVI) – A propane explosion injured several people in St. Louis Thursday night.  The explosion happened on Hall Street not far from Bellfontaine and Calvary cemeteries and Hazmat crews responded to the scene.

Fire officials got the call around 8 p.m.  Officials say workers were operating a forklift inside a trailer with hazardous materials with it.   That’s when somehow a propane tank exploded and caused a flash fire.

Six people were injured. Four were transported to an area hospital. One person is in critical condition and three others are in serious but stable condition.   The two remaining patients did not go to the hospital.

A building was also evacuated as a precaution.

Now fire and hazmat crews are trying to figure out what caused the explosion.

Hazmat teams are now trying to figure out what caused the explosion.