County officials declared the wreck a "mass casualty incident" because of the number of injuries.
Firefighters and paramedics were dispatched to the 7500 block of Washington Boulevard, also known as Route 1, shortly before 7:30 a.m. on July 22 to a report of a motor vehicle collision, officials said.
Units arrived and found two cars, a pickup truck and a 10-passenger van, involved in a collision, officials said.
Thirteen patients were transported with minor injuries to area hospitals: two to Baltimore Washington Medical Center, four to St. Agnes Hospital, two to Harbor Hospital and five to Howard County General Hospital.
The five patients transported to Howard County General Hospital were transported via the county's Medical Ambulance Bus (MAB), a vehicle capable of transporting a large number of victims at one time.
Capacity for the MAB is 14 stretchered patients or 26 seated patients.
Howard County police are investigating the collision.