The unborn babies of two sisters died yesterday after a car in which the women were riding was struck by an ambulance in Anne Arundel County, police said. The crash capped a bloody weekend in which four other accidents on area roads left five people dead and six injured.

The babies of Cathy Ann Sears, 19, and Tammy Sears, 25, both of whom were nine months pregnant, were pronounced dead late yesterday afternoon at Harbor Hospital in Baltimore, said Richard Molloy, a spokesman for the Anne Arundel County Police Department. The women, both residents of Baltimore, were admitted in fair condition, he said.

Molloy said the accident occurred at 2:18 p.m. on Ritchie Highway in Glen Burnie when a northbound ambulance from the Ferndale Volunteer Fire Department, responding to a call for a possible stroke, crossed an intersection against a red light in front of Glen Burnie Mall.

Molloy said the ambulance struck the 1986 Ford LTD in which the Sears sisters and three other people were traveling.

James Johnson, the car's driver, and Tammy Sears's son, Gregory Rutherford, 3, were not injured, the spokesman said. Tammy Sears's daughter, Krystal Chamber, 7, suffered head injuries and was taken to Johns Hopkins Medical Center in Baltimore, where she was in critical but stable condition last night.

Of the car's occupants, only Johnson was wearing a seat belt, Molloy said.

The two ambulance crew members -- Eric Brown, 19, the driver, and Cindy Baucam, 19 -- suffered minor injuries and were treated at North Arundel Hospital.

Molloy said no charges have been filed in the accident pending the outcome of a police investigation.

Earlier yesterday, two men were killed and a third was injured when their car ran off a road in Poolesville and struck a tree, Montgomery County police reported.

Police said the car, a 1990 Chevrolet Cavalier, left Whites Ferry Road just west of Elmer School Road and struck a tree about 2:50 a.m. The driver, John E. Higgins, 19, of Brockton, Mass., was thrown from the car, as was a passenger in the rear seat, Justin L. Norris, 19, of the 24500 block of Whites Ferry Road.

Both died instantly. The third man, Hugo Thomas Pinilla, 20, of New Rochelle, N.Y., was taken to Suburban Hospital, where he was listed in fair condition.

None of the three, all members of the Marine Corps, was wearing a seat belt, police said. Police said alcohol and excessive speed contributed to the crash.

A few hours after that accident, a Forestville man was killed when his car struck the rear of another car, Prince George's County police said.

Keith Delonte Joiner, 20, was westbound on Pennsylvania Avenue about 6:10 a.m. when his 1988 BMW struck the rear of a 1983 Chevrolet Chevette and rolled. Joiner, of the 9500 block of Hil-Mar Drive, was thrown from the car and was declared dead at the scene.

The driver of the other car, Latarsha DuVall, 28, of the 3000 block of W Street SE, was taken to Southern Maryland Hospital. She was listed in serious condition.

On Saturday night, a woman was killed and two men were injured in an accident in Potomac.

Police said a 1990 Toyota Camry was traveling south at high speed on Persimmon Tree Road just north of Bradley Boulevard when the accident occurred at 9:54 p.m.

The car failed to make a curve and ran off the road and into a guardrail, where it skidded 60 feet before flipping and hitting the tree.

Cecelia Bellido Jensen, 47, identified as a resident of Costa Rica, was thrown from the rear seat and killed. The driver, Brian Charles Jensen, 45, of the 9400 block of Turnberry Drive in Potomac, and another passenger, John Jensen-Rubio, 50, of San Jose, Costa Rica, were taken to Suburban Hospital, where they were listed in critical condition. A police spokesman could not say whether the three were related.

Both men were wearing seat belts; the woman was not. Excessive speed and alcohol played a role in the accident, police said.

In another accident Saturday night, a Charlottesville man died after his car crossed the center line on Dumfries Road in Prince William County and struck another vehicle.

Richard A. Laurence, 20, who was driving south near Independent Hill, apparently was not wearing a seat belt, said Prince William County police Cpl. R.L. Reese. The driver and passenger in the other vehicle, who apparently were wearing seat belts, suffered minor injuries in the 9 p.m. crash, Reese said.