Moments after Red Line Train 107 rolled out of the Silver Spring Metro station yesterday morning, the first two cars broke away, marooning the rest of the train on tracks south of the station.

The incident, at 9:07 a.m., stranded scores of puzzled riders who suddenly found themselves in four motionless rail cars without a train operator.

Kevin Fahey, 47, was aboard the third car, which became the first car after the train broke apart.

"We had just left the station and were getting up to full speed when all of a sudden, we came to a stop. I saw this look on a woman's face and turned to see, and you could see daylight -- we were suddenly the front of the train," he said. "Up ahead, you could see the rest of the train going down the tracks."

The last four cars of Train 107 came to rest just south of the station but some distance from the platform, Fahey said. A few passengers in his car got up and hit the emergency intercom to notify the train operator, he said. But no one responded, because the operator was in the first section of the train that had separated.

Cell phones snapped open, Fahey said. "People were calling for help, calling their offices to say they were going to be late," he said. "I called the Metro police. I said, 'You guys need to get your equipment working right.' They said: 'We don't do that. We're the police.' "

The air conditioning in the car in which Fahey had been riding wasn't functioning, and it grew uncomfortably hot, he said. Several passengers opened the emergency bulkhead doors that led to the next car, which was air-conditioned, and everyone filed into the cooler car to wait for rescue, he said.

Although annoyed, no one seemed to panic, he said. "We were aboveground, not in a tunnel, and you could see the station," Fahey said.

When Train 107 broke apart, the brakes on both sections of the train automatically deployed, Metro spokeswoman Lisa Farbstein said. The two sections of the train came to rest seven to 10 feet apart, said Steven A. Feil, Metro's chief operating officer for rail.

Metro Transit Police, after fielding a call from a passenger on the train, notified Metro's operations control center that the train had separated, Feil said.

Controllers then directed the train operator to reconnect the first two cars to the stranded four cars, a move that resulted in a loud thud and a shudder felt by passengers, Fahey said.

After the cars were reconnected, the train operator walked through the rail cars to the car closest to the station and moved the reconstituted six-car train back to the platform at 9:20 a.m., Farbstein said. Passengers were ordered off, and the train was sent to the rail yard for inspection, Farbstein said.

No one was injured, she said. Metro officials did not know how many people were aboard, she said.

The marooned cars were never in danger of being rammed by another train because Metro's rail cars are governed by a computerized system that detects the presence of the stranded cars and would automatically engage the brakes of an oncoming train if it came too close, Feil said.

Travel on the Red Line was slowed because of the incident; two trains had to share a single-track around the problem area, Farbstein said. By late yesterday, transit officials suspected that a faulty valve had caused the mechanical coupler that connected the second and third cars to open. The cars involved are among the oldest owned by Metro and date from the mid-1970s, but the valve in question is supposed to be replaced every four years, Feil said.

It is highly unusual for cars of a moving Metro train to separate. The last time such an incident occurred was Jan. 28, 2004, when a train came apart near the College Park Station because of a faulty coupler, Feil said. Metro officials cannot recall any other similar incidents in recent history, he said.