A collision between two metro trains has left 48 people injured, four of them seriously, The San Francisco Chronicle reported on Sunday.
But none of the injuries are described as life-threatening, the newspaper added.
The incident occurred Saturday afternoon when one train rear-ended the other near the West Portal Station's boarding platform, according to the report.
The most seriously injured was the driver of the L train, who was conscious when paramedics arrived, said the paper.
Three riders were also seriously injured, but all four patients were in stable condition at San Francisco General Hospital.
The crash forced authorities to halt train service in both directions in the area and to shut down the intersection of West Portal Avenue and Ulloa Street, according to the report.
The accident caps a series of metro accidents in the United States over the past month.
Last month, a metro commuter train slammed into the rear of another subway train near Washington, DC, killing nine people and injuring dozens of others.
In May, 49 people were injured when one Boston trolley car crashed into another.
Copyright 2009 AFP American Edition
