An arsonist set fire to the front door of a home in Prince George's County early yesterday in what authorities suspect was the 40th attack in an 18-month string of fires.

A pair of passing newspaper carriers noticed the blaze, in the 6200 block of 49th Avenue in Riverdale Park, about 4:35 a.m. They banged on the side of the house. All eight occupants -- seven family members and a live-in babysitter -- escaped safely.

"I trust in the Lord," said Wylene Davis, one of those who escaped. "He woke us up and got us out in time."

Because the hour was early and the fire was set with an accelerant and near a door, investigators added it to the list of serial arsons.

The fires tied to the serial arsonist began in March 2003 in the District and Prince George's County. Since then, there have been fires in Alexandria and in Fairfax and Montgomery counties, plus one attempted arson in Washington.

Several people have been injured, and one person died: 86-year-old Lou Edna Jones, whose home in Northeast Washington was set ablaze in June 2003. Investigators have released a psychological profile of the arsonist and two sketches of a man seen near some fire scenes.

At one point, authorities arrested a man who seemed to fit the description of the arsonist and had allegedly impersonated a firefighter. But he was quickly ruled out.

The pace of the fires has slowed considerably in 2004, with seven attacks this year after 33 in 2003. Before yesterday's fire, the most recent arson had been in June.

At this point, investigators cannot be certain what this pattern means, said Kelly Long, a spokeswoman for the Bureau of Alcohol, Tobacco, Firearms and Explosives.

"Every time we think we have a pattern, things kind of change," Long said.

Yesterday's fire was set at a corner house where Wylene and Jerry Davis live with four children, a grandchild and babysitter Tia Tyler, 21.

At the time of the fire, Tyler said, she was awake, working on the computer, and 21-year-old Jara Davis was up preparing a bottle for her 11-month-old son.

From outside, they heard a car honking and someone banging on the aluminum siding. Carriers for the Prince George's Gazette had noticed the fire as they drove by.

Inside, the two women looked over and saw the front door ablaze. The alarm went out to the rest of the house.

"I woke up and heard car horns blowing, and then my trusty alarm clock here -- my wife -- was . . . telling me we had to get up, the house was on fire," Jerry Davis said.

All eight escaped through a basement door and soon saw a police officer with a fire extinguisher putting out the fire.

The front door was charred and the siding was melted, causing about $3,000 in damage, said Prince George's Fire Department spokesman Mark Brady.

An eight-inch circle of soot just under the burnt siding marked the spot where the arsonist had left a container full of accelerant that had been used to start the fire, Wylene Davis said.

Yesterday afternoon, as friends and relatives visited the house and brought food, Davis family members said they had been terrified during the blaze.

"Whoever is doing this is sick in the head," Wylene Davis said. "To do this kind of thing is not normal, it's evil."

All said they wanted to thank the two newspaper carriers, a man and a woman, who left the house after they were assured that everyone had gotten out.

"If it hadn't been for them, we'd still probably be in there," said Jerry Davis Jr.

Jerry Davis stands on his porch in Riverdale Park, where a fire was set early yesterday.