It had been several days since Lina Douglah grilled chicken kebabs on the deck of her parents' Sterling townhouse, and the college student thought it would be safe to discard the ashes in a paper bag.

"The ashes were very cold," said Douglah, 25. "I took them out with my hands."

But some of the ashes and charcoal left in the bag on the deck Saturday night were still smoldering, Loudoun County fire officials said this week. The bag caught fire early Sunday, and the flames crept up the vinyl siding of the townhouse and into the attic, causing about $500,000 in damage, including to a neighbor's home.

Douglah was alone in the home in the 20000 block of Miranda Falls when the fire started about 8 a.m. She did not realize how serious it was and called 911 from inside to find out how to extinguish it. But the fire quickly grew in intensity, filling the home with smoke and driving Douglah, still in her pajamas, outdoors.

"If I had slept in my room [at the back of the house], I don't know where I would be," said Douglah, a student at George Mason University. She had decided to sleep in her brother's bedroom the night before because her sheets were still in the wash.

Loudoun fire and rescue Capt. Mike Lamb said a touch test is not sufficient to determine whether charcoal or ashes are safe to store. He also said that a paper bag is the worst place to put ashes and that they should be discarded in a metal container.

"They can stay hot enough to fester for several days," Lamb said, noting the extensive damage the fire caused. "There is no back wall on the top floor. You can see into the house."

Ash-related fires are most common during the winter months, when people clean their chimneys or woodstoves. During fiscal year 2003, the number of fire incidents was highest in December and January, with nearly 500 calls each month, according to county records.

Douglah's father planned to return home today from Sweden, where he owns a business, to assess the damage. Douglah and her family were born in Iraq but are all Swedish citizens. She and her brother are in Northern Virginia to finish their college educations.

The Red Cross paid for a hotel room for Douglah for two nights. She said her family is just happy she was not injured.

"My family told me that this is just a house," Douglah said. "The most important thing is that I got out."