Dou Gardner was sitting in the television room of the Riverdale Heights fire station at about 1 a.m. yesterday when the station's siren began blaring.

"I picked up the phone and called headquarters," he said. "I wanted to see what was going on. I thought maybe we'd missed an address or something."

Headquarters informed him it knew nothing. Then Gardner, 17, noticed that the siren, which normally rings three times and stops, was still blaring.

"Right then I figured it must be in the building," he said. Sure enough, when he checked the second floor hallway, it was choked with smoke. He alerted the five other volunteer firemen spending the night and the men moved the fire equipment form the station to safety.

The sight of this being done startled Acting Riverdale Chief Bernard Loeffel when he emerged from his house across the street. "I've been a volunteer fireman for 29 years, but when I saw what was going on it kind of shook me up," said Loeffel. "I was kind of shocked to see my own firehouse on fire.

By the time other fire equipment arrived, the men had the blaze under control. The fire had been confined to the second floor and was believed caused by an electrical malfunction. Total damage was estimated at about $10,000 but the station was in operation yesterday afternoon.