SAN BERNARDINO (CBS) — A would-be copper thief was gravely injured early Saturday morning when he attempted to steal copper wiring from a live Edison vault, according to authorities.

Witnesses told CBS2 and KCAL9 reporter Melissa Maynarich that the man could be heard screaming in agony.

Jeff Grammatico was across the street from the substation when he said, “I heard a boom.” He added, “It made me jump from one side of the room to the other.”

He ran to the fence and saw a man burning alive. “It was scary. I was trying to cut the gate to get in. It was horrifying to watch him burn.”

Grammatico says he ran back to his home to get a fire extinguisher while another passerby called 911. “He kept standing and screaming, screaming, screaming. And I couldn’t get in. I had a fire extinguisher. But he wouldn’t come over. But he started to roll.”

Officials say the suspect is “extremely grave” and that it’s likely he was burned by 33,000 volts of electricity.

The incident occurred on the corner of Rialto and Stoddard about 2 a.m.

Southern California Edison said about 14,000 customers lost power. Service was fully restored by Saturday afternoon.

The man is described as a man in his 20s. Police have not released the man’s name. Witnesses said he was so badly burned there was no way for him to be identified.  JR Velasquez said it was hard to witness the horror of the man burning. “It was something I really never seen n my life. Never happened to any animal or anybody.”

The man has not yet been charged with a crime. Police are trying to locate his family.