LOS ANGELES — Paramedics evaluated passengers on a Southern California commuter train that stopped after a minor collision with a big rig Tuesday, authorities said.

Train 212 on Metrolink’s Antelope Valley line was heading south toward Los Angeles at about 20 mph when it struck the truck on the tracks shortly after 10:30 a.m., agency spokeswoman Sherita Coffelt said.

The train remained on the tracks about 15 miles northwest of downtown Los Angeles and sustained “very minor damage,” Coffelt said.

Twenty-one out of 187 passengers on board requested medical assistance, Coffelt said. She said least 14 were transported to hospitals, but didn’t know the extent of injuries.

The tractor trailer remained upright and its driver was unhurt, according to Erik Scott, a spokesman for the Los Angeles Fire Department.

The double-decker train blocked vehicle traffic at the crossing for about an hour-and-a-half before moving on.