Five Avis rental cars exploded and 10 more were destroyed or damaged early yesterday in a fire at National Airport that started when an Avis employe fell against a fuel pump during a scuffle with another worker, airport and Arlington fire officials said.

Federal Aviation Administration Fire Marshal Bill Duckwitz estimated damages to the 15 cars, as well as three fuel pumps and the awning over them, at between $115,000 and $120,000.

"There was an altercation between two employes in that area" shortly after midnight, Duckwitz said, adding that the fight apparently was over "something that had been brewing for a couple of days."

Russ James, vice president for corporate communications at Avis headquarters in Garden City, N.Y., identified the Avis employe as service agent Reginald Lockhard and the other worker, an employe for Cleaning Specialists, an Annandale firm that contracts with Avis, as Mitchell Brown.

During a scuffle, Lockhard fell against a fuel pump, snapping a feeder line at the base and releasing fuel onto the ground, Duckwitz said. The jolt broke an electical junction box at its base, setting off a spark that ignited the fuel.

The burning fuel immediately scorched the pumps, the awning and two cars parked nearby, then raced nearly 150 feet down a nearby slope, burning other cars parked in a row, Duckwitz said.

Lockhard was treated for a cut lip at National Hospital for Orthopaedics and Rehabilitation and released. Brown was not reported injured.

"We're still trying to put all the facts together as to what happened and determine who was at fault," he said.

A Cleaning Specialists manager declined to comment.