LAFAYETTE -- A broken power pole crossarm is to blame for a power outage that shut down a portion of Hidden Valley Road in Lafayette on Wednesday, police said.

The outage was reported at 12:46 p.m., PG&E spokeswoman Tamar Sarkissian said, and caused officers to close the roadway between Knox Drive and Crest Road for a few hours.

Crossarms are bolted to poles and are used to support wires and other equipment, Sarkissan said.

When the crossarm broke, two wires made contact with each other triggering the outage. Often that can lead to a loud noise and bright flash of light. Initially police had thought a transformer explosion caused the outage.

PG&E workers on Thursday were still investigating what caused the crossarm to break.

The break initially knocked out power to 1,764 PG&E customers, Sarkissian said.

Power was restored by Wednesday evening.

Contact Natalie Neysa Alund at 510-293-2469. Follow her at Twitter.com/nataliealund.