Overnight traffic on Route-93 was restricted to single lane after a Massachusetts State Trooper was injured while responding to a crash.

According to the state police, an unnamed trooper assigned to the Milton Barracks was responding to a crash between exits 3 and 4 when a “secondary crash” occurred, injuring the officer.

“The Trooper was standing outside his cruiser, in the process of investigating the initial crash, when he was struck by the approaching vehicle. The driver of that vehicle was transported to a local hospital with non life threatening injuries,” a state police spokesman wrote in a release.

The trooper was transported to a Boston hospital where he remains in stable but serious condition. His family and other troopers are by his side, according to the spokesperson.

“This incident serves as a reminder of the dangers law enforcement officers face every time they leave home and assume their role as public safety professionals,” State Police Colonel John Mawn Jr. said in a statement.

The second crash and subsequent investigation led to the closure of all three northbound lanes of the busy highway, with traffic restricted to the breakdown lane for hours.

The driver of the vehicle causing the trooper’s injuries has not yet been charged with any violation, though the investigation is ongoing, the spokesman said.