OAKLAND (CBS SF) — The right lane and off-ramp of westbound Interstate Highway 580 at Broadway are closed because of police activity Monday morning, the California Highway Patrol said.

Authorities first announced the traffic advisory at 9:15 a.m. on the 511.org Twitter account.

Motorists are advised to expect delays and use alternate routes. As of 9:30 a.m., the left and center lanes of the freeway are open, but there is still police activity in the area.

A CHP spokesman did not immediately disclose the cause of the delay. There is no estimate for when the highway will fully reopen.