Members of a Northern Virginia volunteer fire department were so proud of their new $6,000 "Hurst" tool that they held a special demonstration yesterday to show how it could quickly cut into an automobile to rescue people trapped in wrecks.

As a crowd of 40 looked on, two members of the Burke Volunteer Fire Department in Fairfax County quickly ripped a door from a 1969 Buick parked near their fire station. Then they pulled the car's steering wheel through a windshield and knocked out the windows.

At that point, a voice cried out: "Hey, what have you done to my car?"

"The guy was very hostile," said one onlooker. "Actually he was livid."

Bill Burris president of the Burke fire department, said the man had reason to be upset. The fireman, in their enthusiasm to show off their new tool, had cut up the wrong car, he said.

"It was just a mistake, Burris acknowledged. "Everything has been taken care of," he said, declining to name the man whose car was destroyed.

Burris said the department will pay the man for the loss of his car. "It's just a mistake. It's just a mistake," Burris kept saying.