A van carrying 13 mentally retarded adults plowed into the rear of an autombile during the height of yesterday morning's rush hour traffic, creating what an Arlington police spokesman called "a day of heroes" as passers-by pulled the injured from the burning vehicles.

Sixteen persons were injured, one critically, in the Arlington collision, one of many in the region as a light rain made roads slippery.

Arlington police spokesman Tom Bell credited four motorists with helping rescue the 13 mentally retarded adults and a 7-year-old girl from the wreck at Henderson Road and Arlington Boulevard (Rte. 50). The driver of the car was trapped inside the vehicle and had to be extricated by crews who cut into her automobile with special saws.

Bell said Edward Henderson, a courier with the Five Star Courier Service in Alexandria, rescued the young girl.

"He was a real hero. He probably saved that little girl's life," Bell said. "He reached right through the window, through the flames, and pulled her out."

The girl, Jamie Abrecht, a first grader at Barrett Elementary School, was taken by ambulance to Arlington Hospital, where she was listed in fair condition with burns on her face and back.

Her mother, Nancy Beck of 210 N. Glebe Rd., the driver of the car, was the most seriously injured. She was listed in critical condition last night with a broken neck and severe burns over half her body at the Washington Hospital Center.

Police said the car, heading west, had stopped for a traffic light when the van, driven by Carla Gardner, 23, of 2037 N. Woodrow St., hit it from the rear.

She was charged with reckless driving.

Neither Gardner nor her 13 passengers were injured seriously, police said. They were also rescued by three other persons who entered the smoke-filled van to unbuckle the seat belts of the screaming passengers and lead them to safety.

Beck was pinned in the 1974 Dodge Dart, which skidded 125 feet into a ditch after the collision. Fire Department spokesman Stevan Hynson said she had to be extricated through the roof of the carwith special equipment known as "the jaws of life."

A dental assistant and two employes of the Brazilian government rescued the 13 retarded adults in the van, who were on the way to work at the Sheltered Occupational Center of Northern Virginia at 750 S. 23rd St.

"The van was on fire on the outside and the inside was filled with thick smoke. They were just sitting there and screaming because they didn't know what to do," said Jaya Pal, the dental assistant.

She said that Roberto da Rosa, an employe of the Brazilian Aeronautical Commission, entered the burning van, unbuckled the passengers' seat belts and directed them to her and da Rosa's wife Edilia, who works at the Brazilian Embassy.

"They were frightened and some were hurt," said Edilia da Rosa, who works for the embassy's army attache. "We were afraid something else might happen, so we got them to a safe area as quickly as we could."

"It all happened in a split second," she said. "Suddenly, we see this fire and a car sort of skidding and crossing almost in front of us. The lady driver was crying out for help and asking us to get the people out of the van."

Moments later, police commandeered a school bus and told the driver to take nine of the passengers to Arlington Hospital. The driver and the passengers were taken by ambulance to Northern Virginia Doctors Hospital. All were treated and released.

The fire department's Hynson said that Gardner said she was "distracted by someone in the rear and she turned around to look. When she looked back, the light had changed and she couldn't stop."

The Maryland State Police said rain-slicked roads may have caused six accidents on the Capital Beltway yesterday morning, all near River Road, contributing to a 10-mile backup on the Beltway.

Sgt. Ken Frick said of the six accidents reported at the Beltway and the Cabin John Parkway, three were serious enough to be investigated. No one was injured, police said.