Raymond Illig was just "sitting chatting" with his family and some friends on the front lawn of his Rockville home about 9 p.m. Saturday, when he saw a neighborhood youth barreling toward the side of his house in a 1973 Ford Gran Torino.

Seconds later, as the Illigs looked on in amazement, the car rammed into the side of their house, crashing through the master bedroom and part of the kitchen.

"You ever been in the Army . . . well it sounded like a 105 piece of artillery going off," Illig said later of the sound the crash made.

According to Montgomery County police, the 13-year-old son of one of the Illig's neighbors had decided to warm up a friend's car just before he and his mother went shopping for shoes. The youth backed the car out of the driveway, then attempted to drive it back but panicked and overac celerated, police said.

He drove the car off the curb, sideswiped a tree and hit a fence at 4804 Mercury St., then headed directly toward the Illigs' house at 4806 Mercury St., police said.

"I was just concerned for my son . . . he was in the house," Illig said. But neither Illig's son, nor the youth who was driving the car, nor another teen-ager who was a passenger, was injured, police said.

The teen-age driver was issued a county summons for operating a motor vehicle without a license. The damage to the car was estimated at $1,500; between $5,000 and $10,000 in damage was done to the house, police said.