Comment on Accident slows traffic on 580

An accident involving two vehicles on Interstate 580 slowed traffic to a crawl Saturday night. The collision occurred on the Marin side of the Richmond bridge, causing two lanes to be initially blocked. The last lane reopened around 8 p.m., about an hour from when the California Highway Patrol issued a Sig alert. There did not appear to be any major injuries, the California Highway Patrol said. Wendy Lee is a San Francisco Chronicle staff writer.