Route 50 in Queen Anne's County was closed in both directions Thursday following an accident during which a car traveling the wrong direction hit four other vehicles.
Officials say three people, considered to be in serious condition, were transported to local hospitals.
The accident reportedly happened at 3:15 p.m. As of 3:45 p.m. there was already a 5-mile backup.
Route 50 was expected to remain closed for several hours.
Officials say the fork at Highway 301 was not an option for a detour. Drivers were advised to look for alternate routes.