Southbound traffic headed to the Harbor Tunnel slowed Monday morning after a chain-reaction crash involving four vehicles blocked the left lane of Interstate 895, according to a Maryland Transportation Authority Police spokesman.

Medics responded to the collision, reported just past exit 12 at about 7:20 a.m., but the injured declined treatment at the scene, said Sgt. Jonathan Green of the Maryland Transportation Authority Police.

The right lane and shoulder remained open, he said, and the scene was cleared by 7:51 a.m., although traffic continued to be slow after that.