A 2-year-old boy was killed and six people were injured in a fiery four-vehicle crash yesterday morning in Fairfax County that closed the westbound lanes of Interstate 66 for two hours and paralyzed secondary roadways, police said.

The chain-reaction crash occurred west of Route 123 about 9:45 a.m., when the driver of a Chevy pickup rear-ended a Geo Metro, which burst into flames, said Sgt. Wallace Bouldin, a Virginia State Police spokesman. The Geo then struck a Buick, which in turn hit another car, a Toyota, he said.

The boy killed in the crash was a passenger in the Geo, and the driver, who is pregnant, was critically injured, he said. Both were from Fairfax County, authorities said. The victims were not identified further because relatives had not been notified, Bouldin said. Five other people were injured, including two retired Fairfax firefighters who attempted to rescue the passengers from the burning vehicle, said Dan Schmidt, spokesman for the Fairfax fire department. They suffered burns to their hands and arms and were treated at a hospital and released, he said.

The boy was pronounced dead at the scene, and the injured were transported to Inova Fairfax Hospital and Inova Fair Oaks Hospital. One person was later transferred to Washington Hospital Center's burn unit, according to Bouldin.

Police charged the driver of the pickup, Matthew R. Cable, 21, of Hagerstown, Md., with reckless driving, Bouldin said. He said Cable was distracted while reading a map. Cable, who was injured, was treated and released from a hospital.

Bouldin said the Fairfax County Fire and Rescue Department will investigate why the car caught fire.

The crash caused delays on several secondary roadways, including Routes 50 west and 29 south.

"It was terrible," Bouldin said. "We had traffic jams everywhere."

Fairfax County police established a command center at the site, where police officers from the county, the state police and Fairfax City helped redirect traffic onto Route 123.

Fairfax City Police Chief Richard J. Rappoport said the traffic jam was "certainly among the worst" he has seen.

"It's very seldom that [Interstate] 66 is literally closed to all traffic," he said. "There was extremely heavy volume. It was worse than rush-hour traffic."

Police barred drivers from entering the interstate and used the on-ramps to direct traffic off the interstate. Drivers could either go north on 123 toward Fairfax County or south toward Fairfax City, he said.

The lights were changed to the rush-hour cycle, but that alone did not accommodate the rush. Rappoport said officers had to direct traffic.

Police said the cars involved in the crash were cleared by noon and the interstate was reopened. Traffic returned to normal by about 2:30 p.m., police said.

So far this year, 478 fatalities have been recorded in Virginia, down from 495 at this time last year, said Bud Cox, an analyst with the bureau of field operations for the Virginia State Police. He said that safety belt usage is at an all-time high -- 79.9 percent -- in the state.

"It's the single most important thing a person can do to protect themselves in a crash," he said.