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"He was giving me money. He put his hand in his pocket," gas station employee Jassie Singh told WFIE. "Suddenly, there was a blast in his pocket and then there was a fire. A big fire and he was burning."

Singh said he wasn't sure what was happening when Hamilton ran out of the store, struggling to get out of his burning pants.

Singh can be seen on surveillance video using a fire extinguisher to put out the fire on Hamilton.

Hamilton went to the bathroom to check out the burns before another customer drove him to the hospital.

In a Facebook post, Hamilton said he had-third degree burns on his leg.

He is still able to walk.

A faulty spare battery may have been the cause of the explosion.