A small grass fire shut down part of Highway 101 in Healdsburg and caused major traffic delays, made even worse by a crash involving multiple cars.

Healdsburg police first issued a notice about the fire at 3:25 p.m., urging motorists to use Healdsburg Avenue after the northbound lanes were closed at Dry Creek Road. One lane reopened a half-hour later.

At 5 p.m., police reported a four-car crash in the area was “adding significant delays.” All lanes were reopened by 6:22 p.m. but police still asked drivers to be cautious.

The 4.5-acre blaze burned some brush but didn’t threaten any structures or prompt any evacuations, according to Cal Fire spokesman Will Powers. He said at about 5:30 p.m. firefighters had contained and were mopping up the blaze.

Firefighters from Cal Fire, Healdsburg, Windsor and the Sotoyome Volunteer Fire Company responded to the blaze, Powers said. The cause is still under investigation.

You can reach Staff Writer J.D. Morris at 707-521-5337 or jd.morris@pressdemocrat.com. On Twitter @thejdmorris.