A Gaithersburg couple and their baby daughter were killed last night in a head-on auto collision on a two-lane road in a rural section of upper Montgomery County.

Two other children of the couple were injured in the collision onGaithersburg-Laytonsville Road along with the driver of the second car.

Cpl. Phillip Caswell, a Montgomery County police spokesman, said the second car, which was going south, failed to negotiate a right-hand curve, crossed the center line, and struck the couple's car, which was headed north.

The accident occurred about 6:45 p.m. about three-quarters of a mile north of the Montgomery County Airpark.

Police said it appeared that the father, identified as Alan Donald Lighthall, 31, of 58 Nina Ct., was driving the family's 1980 Pontiac Phoenix.

The mother and the baby girl were believed to be in the front seat as well. The two surviving children, both boys, apparently were in the rear seat, police said.

The mother was identified as Tana Lynn Godfrey Lighthall, 27, and the baby as Rebecca Lynn Lighthall, about 14 months.

Authorities said the father was pronounced dead on the scene, where the two smashed cars came to rest in the stubble of a harvested cornfield.

The mother and the baby girl, who witnesses said had been hurled through the car's windshield, were pronounced dead at Shady Grove Adventist Hospital.

The two surviving boys were taken first to Montgomery General Hospital, then flown by helicopter to Johns Hopkins University Hospital in Baltimore.

They were identified as Brian Lighthall, 5, and Nathan Lighthall, about 4. Nathan was reported in critical condition last night. His brother, who suffered two broken legs, was believed in less serious condition.

Police did not release the identity of the youth who drove the second car. They said he was taken to Montgomery General Hospital suffering from a broken leg.

No charges had been filed in the incident as of late last night.