The two teenagers, best friends for years, had just left a Germantown bookstore Monday evening when the accident occurred. Somehow, about 8:15, the youths' Ford Bronco collided with a car, killing its passengers.

Yesterday, Montgomery County police continued an investigation to determine the cause of the collision, which killed two brothers and left the two teenagers injured.

Police yesterday identified the dead brothers as Michael Murad, 42, of the 12200 block of Major Drive in Germantown, and Matthew Murad, 31, of 1714 Abercromby Court in Reston. The driver of the Bronco, Blake Edward Powell Beadle, 17, of the 23400 block of Ridge Road in Germantown, remained in fair condition at a hospital last night. His passenger was treated at a hospital and released.

The accident occurred about 8:15 p.m. Monday, when Beadle's 1987 Ford Bronco, traveling north on Frederick Road at Gunners Branch Road in Germantown, struck the passenger's side of Matthew Murad's 1996 Subaru Impreza as he tried to make a left turn into a shopping center parking lot, police said.

The Bronco's impact was so severe it slammed the Subaru into a steel utility pole, witness said.

Investigators have ruled out alcohol as a cause of the accident. Skid marks were found on the road, and preliminary reports show there were no mechanical problems with either vehicle, police said.

Patrons of the Fox Chapel Shopping Center and a nearby fast-food restaurant rushed to the scene of the crash to offer aid to victims, and many phoned 911.

When paramedics arrived, the Murad brothers were trapped in the car, held in place by seat belts. Both were in cardiac arrest, police said. Ambulances rushed them to Shady Grove Adventist Hospital within minutes, but doctors were unable to revive them.

Beadle, police said, was not wearing a seat belt, but he was not thrown from the vehicle. His passenger, Charles Joseph Schulz, 17, of the 24200 block of Laytonsville Road in Gaithersburg, was wearing a seat belt.

Schulz was taken by ambulance to Shady Grove Adventist Hospital, where he was admitted overnight before being released yesterday, said his mother, Cathy Schulz. Beadle was taken by U.S. Park Police helicopter to Suburban Hospital, where he was listed last night in fair condition, a hospital spokeswoman said.

The Murad brothers spent much of their youth in a ranch-style house in a Germantown subdivision. Their father, Ronald Murad, was an engineer, and their mother, Gloria, was primarily a homemaker, said a neighbor, Mariana Limbaugh.

Matthew Murad attended Gaithersburg High School and later married Constance Murad. He worked for an oil company, Limbaugh said. Records show that Murad had addresses in the Central Asian nation of Kazakhstan and in Dallas. In 1996, records show, Matthew Murad sold a home in suburban Chicago and used his parents' Montgomery address as a permanent one. Little could be learned about Michael Murad yesterday.

The bodies of both men were taken to the Maryland medical examiner's office in Baltimore for autopsies, officials said.

Monday's accident was the second fatal collision in Montgomery County in the past week. On Friday, two teenagers were killed when the car in which they were riding spun out of control on a wet Glen Echo road and struck a tree.

In the first six months of this year, 17 people died in traffic accidents in Montgomery County, said police spokesman Derek Baliles. Forty-one people were killed last year, down from 50 in 1997.