COVINA — An underground electrical vault explosion overnight knocked out power to the eastern portion of Downtown Covina early Saturday, officials said.

The electrical vault, buried beneath an alley in the 100 block of East College Street, failed and exploded just before midnight Friday, Covina police Sgt. Ray Marquez said.

The explosion damaged the roadway and cut off power to a section of town from College Street south to Badillo Street, as well as from Citrus Avenue east to Barranca Avenue, the sergeant said.

Power was largely restored to the area by the early morning hours, with the exception of a traffic signal that remained blacked out at College Street and Second Avenue, officials said. A Southern California Edison crew remained on-scene making repairs into the afternoon.