UPDATES: Police are searching for a truck driver who caused an 18-vehicle pileup on I-270 in Germantown Monday morning.

GERMANTOWN, MD — An unidentified white tractor-trailer that made a quick lane change caused an 18-vehicle crash that left four people injured on Interstate 270 south in Germantown Monday morning, officials said. EMS declared the crash a Mass Casualty Incident and are searching for the truck driver who caused the accident and sped away from the scene.

Police were called to the scene between Middlebrook Road and Montgomery Village Avenue at about 5:20 a.m. 

Officials said the crash was caused by an unknown white tractor-trailer that abruptly moved into the far right lane of the four-lane highway.

The unsafe lane change caused other vehicles to rapidly brake in an attempt to avoid colliding, police said.

Maryland State Police troopers determined that the collision involved eighteen vehicles—three tractor-trailer trucks and fifteen passenger cars or SUVs.

"There's not a whole lot we're going to be able to do based on the description," Sgt. Adam Matthai told WTOP. "How many white tractor-trailers are there? So unless someone were to come forward with more information, there's not a very good shot we could identify the vehicle."

Medical crews evaluated more than two dozen people and transported four to the hospital, Montgomery County spokesperson Pete Piringer said. Two people have serious but non-life-threatening injuries.

All four Southbound lanes of I-270 were shut down for about two hours during rush hour because of heavily damaged vehicles disabled in the roadway. All travel lanes were reopened by 8:23 a.m.

One of the trucks involved was carrying a load of slate rocks and numerous large boulders that covered the lanes of travel, further complicating recovery efforts, police said.

A Montgomery County bus was used to shelter the numerous vehicle occupants and witnesses while personnel worked to clear the scene. 

Fifteen vehicles were towed from the scene.

The unknown white tractor and trailer (box style trailer) was last seen stopping briefly on the right shoulder after the collision. The driver continued Southbound on I-270 away from the scene, police said.

Any member of the public who may be able to assist in identifying the suspect vehicle or who witnessed the collision is encouraged to contact the Maryland State Police Rockville Barrack at 301-424-2101.