Emergency dispatchers received a call about an explosion around 3:30 a.m. at Cutting Blvd and South 2nd St.
When crews arrived, they discovered a manhole was blown off with a deceased person inside the vault.
During the investigation, officials say the person came in contact with energized lines and was likely electrocuted, according to Deputy Fire Chief Aaron Osorio.
The person was found above 4 to 6 feet of standing water.
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The Richmond Fire Department is waiting for PG&E to deenergize power in the vault, so they can safely remove the person's body.
The area will remain closed to traffic for a few hours.
The person has not been identified and it's unclear why they were in the vault.