A bomb threat at the West Oakland BART station on Wednesday morning shut down all traffic at the station for nearly an hour and caused major delays throughout the east San Francisco Bay area, authorities said.

The station was evacuated shortly after 8 a.m. when someone shouted there was a bomb aboard a train, according to BART spokesman Linton Johnson.

Police gave the all-clear about an hour later and service was resuming, BART officials said. It was unclear whether anything was found.

A phone call to Oakland police wasn't immediately returned.

Bay Area Rapid Transit serves the Bay Area.