Traffic is at a standstill on the upper deck of the San Francisco-Oakland Bay Bridge as authorities negotiate with an armed man who called in threats.
The California Highway Patrol says it halted westbound traffic during the morning rush hour Thursday after the man reported having a gun. The patrol tells the Contra Costa Times that he also reported having a pipe bomb.
Footage from television news helicopters shows a man standing outside his SUV near the railing of the bridge while on a cell phone.
Authorities have not discussed a motive.
Eastbound lanes on the lower deck of the span remain open.
An average of 280,000 motorists use the iconic bridge each day.