One person was killed and five were injured yesterday in a five-vehicle accident on the Capital Beltway near Rte. 50 that backed up traffic for eight miles and trapped hundreds of holiday beach-goers for almost four hours.

Maryland state police rerouted some of the southbound traffic onto two of the northbound lanes of the Beltway for about two hours after the 9:03 a.m. accident, which occurred a half-mile north of Landover Road (Rte. 202) and about two miles south of Rte. 50, officials said.

But the southbound lanes, blocked by an overturned dump truck and its spilled load of sand, were backed up as far as Rte. 1 and not fully cleared until shortly after 1 p.m., they said.

The backup on the Beltway prevented many would-be beach-goers from reaching Rte. 50, temporarily causing lighter traffic than expected over the Bay Bridge, according to a bridge spokeswoman.

Pronounced dead at the scene was Robert Edward Borwegen, 27, of 7604 Marion St., Forestville, according to police. Borwegen, who was thrown from his vehicle, was not wearing a seat belt, police said.

Three of the five persons injured were taken to area hospitals by helicopter, police said.

Among those injured when their southbound car was struck head-on were Luis and Miriam Cartagena of Amityville, N.Y., and their 3-year-old daughter Jennifer.

Luis Cartagena, 32, was listed in critical condition yesterday at Prince George's Hospital Center. Miriam Cartagena, 27, was in serious but stable condition, the hospital said.

Jennifer Cartagena was listed in serious condition last night, according to a spokeswoman.

Two women, who were in separate cars, were also taken to the hospital center. Police said Rebha Reno, 27, of 2123 Scott Key Dr. in District Heights and Michelle Dowd, 28, of 5446 85th Ave. in New Carrollton were treated for minor injuries and released. It was not immediately known whether any of the five was wearing a seat belt.

Police said the driver of the truck apparently did not require treatment.

According to police, the accident occurred when a northbound Dodge Colt, driven by Borwegen and traveling at high speed, sideswiped a Plymouth Sundance, which was also traveling north.

Both vehicles crossed the median strip and struck the Cartagenas' southbound Ford Mustang in the left lane, police said.

The force of the collision pushed the Mustang into a Toyota Corolla, which was southbound in the next lane.

At the same time, the Plymouth recrossed the median, coming to a stop on the northbound side of the Beltway, police said.

The driver of the fifth vehicle, a southbound dump truck traveling in the far right lane, took evasive action by driving off to the right into an embankment, which caused the vehicle to overturn, police said.

The truck's load of sand spilled across the far right lane of the southbound Beltway, police said. Staff writer Nell Henderson contributed to this report.