An ambulance carrying three medics and a patient from Washington County Hospital was involved in a deadly accident on Interstate 70 near Baltimore.

"The female driver of the ambulance was pronounced dead here at the scene and we had three additional passengers… air-lifted to [Shock] Trauma Center," said Sgt. Thornnie Rouse with the Maryland State Police.

The ambulance is owned by Mid-Maryland Medical Transport. Police said the ambulance driver killed was 27-year-old Jeanette Roseberry from the 18000-block of Herr Lane in Boonsboro.

The passenger in the front seat of the ambulance was 34-year-old John Bagley, Jr., an ambulance attendant from the 500-block of Church Street in Hagerstown. A nurse riding in the back of the ambulance, 31-year-old Robin Banfe of Crystal Falls Drive in Smithsburg, was ejected during the crash. Both were flown to Shock Trauma in Baltimore in serious condition.

The ambulance was transporting a pregnant patient, 22-year-old Maria Williams of Sumans Avenue in Hagerstown, when it crashed. Maryland State Police described the transport as a routine patient transfer between Washington County Hospital and Johns Hopkins Bayview Medical Center in Baltimore. The ambulance did not have its emergency lights or siren activated. Williams was also flown to Shock Trauma with serious injuries.

Police said the ambulance was traveling eastbound on I-70 when, for some reason, it crossed over into the westbound lane and smashed head-on into a tractor-trailer. That tractor-trailer then hit another truck, and spilled its load of lumber all over the roadway. Neither truck driver was injured in the crash.

"Troopers arrived on the scene along with rescue personnel, and learned that a private ambulance was traveling, being operated eastbound in lane number one. For reasons unknown, according to witnesses, the vehicle left the travel portion and traveled through the median, the center grass median, and side-swiped the tractor and trailer hauling lumber products traveling in lane number one," said Rouse.

The person answering the phone at Mid-Maryland Service Transport said the company would not be speaking to the media. Maryland State Police say the investigation continues.