The accident occurred at the intersection of Route 1 and Trappe Road.
Monitored emergency radio broadcasts initially said one to two people may have been trapped.
"Crews from Darlington VFC work an automobile accident with entrapment at intersection of Route 1 (Conowingo Rd and Trappe Rd). Plan an alternate route if you plan to travel in that area," the Harford County Fire and EMS Association public information officers advised on their Facebook page.
A duty officer at the Maryland State Police Bel Air Barrack said a single vehicle was involved and any injuries appeared to be minor.
Route 1 northbound was still closed in the area at 12:10 p.m., State Police said.