Two suspicious blazes broke out in separate areas of Fairfax County within five minutes of each other just before dawn yesterday, damaging a Vienna restaurant and doing $30,000 damage to a Herndon school.

Maintenance workers discovered a fire at 5:33 a.m. in the rear of the Vienna Inn, a hot dog and chili restaurant at 120 Maple Ave. Five minutes later, neighbors reported smoke coming from the Herndon Intermediate School at 901 Locust St., according to Stephanie Strass, Fairfax County Fire Department spokeswoman.

Fire officials said they suspect both fires were deliberately set.

Flames broke out in five locations at the school, but most of the damage was contained in the an auxiliary gymnasium, said Tom Hamton, director of design and construction for Fairfax schools. He said the fire burned through the gym's door and floor.

Other fires were discovered outside the school near another gymnasium, a home economics department door, and two classroom windows, fire officials said.

School officials said their estimate of damages may be higher once they have calculated the extent of damages to the building's contents.

The other fire apparently started in the rear of the restaurant and caused an estimated $15,000 damage, according to fire marshals. The dining area and kitchen were not damaged by the blaze. Fire officials said one of the men who reported the fire had been sleeping in the building and was awakened by smoke.

Vienna Inn owner and manager Mike Abraham closed the restaurant for breakfast and lunch yesterday, but it was reopened by 4 p.m.

Fire officials declined to say how the fires may have started. No arrests have been made in either of the cases, they said.