PG&E crews were investigating.

The cause of a power outage Wednesday.

Night that has left 5,066 Berkeley.

Oakland customers in the dark.

Power went out at 9:59 p.m.

All but 335 of the customers are in Berkeley.

JD Guidi, PG&E spokesman.

Said crews are in the area looking into the cause. 

There was no estimated time for restoration.