One person was killed and three others injured yesterday near Hancock, Md., when a small private plane crashed into the Potomac River after hitting a heavy utility line that then struck and flipped over a moving car, according to Maryland State Police.

Killed in the crash was Cara Rohrer, 20, of Big Spring, Md., who police said was dead when rescue workers brought her up from the overturned and partially submerged plane, a Cessna 172. Hancock is about 20 miles west of Hagerstown.

Sgt. Richard Brown, of the Maryland State Police at Hancock, said the plane's pilot, Donald Alt, 21, of 1715 Strand Ave., Westminster, Md., was taken by helicopter to Washington County Hospital for treatment of multiple leg fractures. He was listed in guarded condition late yesterday.

The crash occurred at about noon yesterday when the plane hit a guy wire that protected a 34,500-volt line and nose-dived into the river. The dangling wire then became entangled in an axle of an eastbound car below it on Interstate 70, flipping the car over.

William Logan, 52, of 8546 Pleasant Plains Rd., Baltimore, who was riding in the car struck by the wire, was treated for lacerations to his face and later released from the hospital. His wife, Miriam Logan, 48, was admitted to Washington County Hospital for observation, officials said.

Brown said that Alt and Rohrer were probably out for a pleasure ride when the plane struck the wire. Officials were not sure yesterday what airstrip the two had left from earlier in the day or where they were headed. Police said Alt did not file a flight plan at the airport in Martinsburg, W. Va., the nearest designated flight facility.