At about 5:20 a.m., 18 vehicles crashed on I-270 in Germantown. Four people were taken to local hospitals. Credit: Via Pete Piringer

State police investigators believe a white tractor trailer truck making an unsafe lane change was the cause of an 18-vehicle crash on I-270 on Monday morning, a department spokesman said.

The crash left four people injured and closed all the southbound lanes of the highway near Middlebrook Road in Germantown for about two hours after 5:20 a.m.

State police are looking to identify the white tractor trailer and its driver, who allegedly cut off a vehicle in the slowest lane, causing that vehicle to slam on its brakes, which started a chain reaction crash behind it, Elena Russo, a state police spokeswoman, said Monday afternoon.

“Right now we’re looking for anybody with information about that white tractor trailer, looking for a tag number, any descriptive information about the truck or the driver of the truck itself,” Russo said.

Investigators don’t know where the truck was heading or what company it was from, she said. The driver did not remain at the scene.

The ongoing investigation will determine whether the driver could be facing charges, she said.

Of the 18 vehicles, three were tractor trailers, one of which was pulling a flatbed carrying slabs of slate, Russo said. That truck did not overturn, and was not at the front of the crash. The slate slabs, which fell onto the road, complicated the cleanup effort and may have contributed to more cars crashing, she said.

Montgomery County Fire & Rescue Service spokesman Pete Piringer wrote Monday morning that about two dozen people were evaluated at the scene. Four people, including two trauma patients, were taken to local hospitals—two to Suburban Hospital in Bethesda and two to Adventist HealthCare Shady Grove Medical Center in Rockville.

State police are carrying out an accident reconstruction of entire incident to determine exactly what happened, Russo said.

Authorities began to reopen lanes of the highway at about 7:30 a.m., though delays continued on the highway and on the surrounding roads through the morning.

Police have asked anyone with information about the crash or the white tractor trailer to call the Rockville barracks of the state police at 301-424-2101.