A crash involving about 20 cars caused closures on I-270 South Monday morning, according to the Maryland State Highway Administration.
Early Monday morning, all lanes were closed on I-270 South past exit 13A at Middlebrook Rd and have since reopened.
Officials said the crash happened around 5:20 a.m.
A tractor-trailer carrying a load of gravel and stones crashed and lost its load.
Other cars in the area were not able to avoid crashing, according to Montgomery County Fire and Rescue.
EMS is evaluating several patients.
At least four people had to be transported. Some of the injuries are serious, but none of them appear to be life-threatening.
This is a mass casualty incident, according to EMS.
