Just when BART riders were told that a train derailment Sunday would not affect their Monday morning commute, two separate incidents delivered delays.

A mechanical trackside problem in downtown San Francisco and police activity at West Oakland station caused delays of about 15 minutes or more Monday morning.

The trackside mechanical problem between the Embarcadero and Montgomery stations was remedied around 6:45 a.m., spokesman Linton Johnson said.

The police activity was cleared up as of 9:30 a.m., an agency dispatcher said.

On Sunday, BART service was disrupted well into the night after a train derailed in Concord. The agency’s crews worked to remove the disabled train from the tracks Sunday night with a crane. The problem was cleared before the morning commute.