Prince George's County fire investigators yesterday sifted inch by inch through the debris left behind by a Seat Pleasant house fire that killed six children on Thanksgiving Day. As they searched for clues, donations from people touched by the holiday tragedy poured into a nearby church -- offerings of clothing, food and money for the family that lost almost an entire generation.

Members of James H. and Annie Mae Williams' family who survived the fatal fire huddled yesterday at the small apartment of a relative, giving statements to fire investigators and taking a stream of messages from sympathetic friends and strangers. They also tried to sort out the early-morning chaos that killed a son and five grandchildren.

"I'm so confused," Annie Mae Williams said as Seat Pleasant Town Council member Joan D. Perry tried to console her. "I'm still not sure what happened."

Fire investigators had not affixed a cause for the fire, but Maj. Thomas Brinkley said they have determined that it started on the first floor of the modest two-story frame home at 203 69th St. Investigators said the fire began toward the front of the building in the living room or the dining room.

Fire officials found a battery-operated smoke alarm in the Williams home, but did not find a battery inside.

The Williams family was asleep when the fast-moving fire broke out around 8 a.m., according to fire officials, who cited the timing as a factor that contributed to the adults' inability to save the children.

Brinkley said that sleeping occupants of a burning building often inhale toxic gases, including carbon monoxide, that disorient them. Brinkley said that people who wake up in a house fire, surrounded by intense heat and dark smoke, often go into shock and are unable to think clearly. Those circumstances often account for the dramatic scenes outside of burning houses where family members exposed to fresh air suddenly realize that other family members are trapped inside, he said.

"The toxic gases disorient you," Brinkley said. "That's why smoke alarms are so important."

All six of the children died of smoke and soot inhalation, said a spokeswoman for the state medical examiner, who ruled the deaths accidental.

Although there were reports that some members of the family had been awake and preparing a Thanksgiving Day meal when the fire started, both fire officials and a member of the family said all of the adults were asleep.

"No one was up," said Anthony Williams, James and Annie Mae Williams' son who lives nearby.

"They awoke out of a sound sleep and nobody knows how it started," said Anthony's wife, Sonja Williams.

The seven adults who had been sleeping in the Williams home were treated for shock, smoke inhalation and minor injuries. Two children were rescued by their uncle, James Kelvin Williams, who had been asleep in a first-floor bedroom.

Investigators spent part of yesterday afternoon cutting out pieces of the floor that will be sent to a laboratory and checked for chemicals that could have helped the fire spread as quickly as it did. The lab also will examine small electrical appliances, including a kerosone heater that was located in the center of the first floor.

"It is going to take some time" to pinpoint the cause, Brinkley said. "We're looking at so much destruction. The first and second floors are pretty much gutted."

About a half mile from the Williams' home at the Faith Temple Number 2 Baptist Church, volunteers answered the constantly ringing telephone and collected donations that by yesterday afternoon filled a hallway almost halfway to the ceiling. The donations, including cash contributions, came from Calvert County, Md., Loudoun County, the District, and elsewhere.

Donations came from people such as cabdriver George Wilson of Arlington, who said he could not distance himself from the tragedy. "It touched me," said Wilson, who left $20 for the family at the church. "It's been on my mind all day. I have three kids and it's something you don't forget. I'll think of it next Thanksgiving."

Another donor, 28-year-old Charles Moore of Fourth Street in Northeast Washington, said he had lost a sister to cancer two years ago, and she left behind three children. "It was traumatic for me and I lost only one relative," Moore said. "It has to be terrible for them, losing six children. I was in tears when I read the story. I felt like I had to do something."

Other contributions and offers of help poured in throughout the day. A District funeral home offered to provide six caskets at no charge, while an anonymous man offered to pay for the funerals of the six small children, tentatively scheduled for Tuesday.

The fire personnel who responded to the blaze assembled afterward at the nearby Seat Pleasant fire station, where counselors from the county's Employe Assistance Program offered counseling to firefighters who may have been overcome by the tragic scene of dead children lying on the floor of the second story. According to fire department spokesman Tony DeStefano, the session is held whenever fire personnel are involved in critical incidents.

"If you could see the size of these kids," said Lt. Jeff Williams, a volunteer at the Seat Pleasant station, "they look like play dolls."

When the first fire call went over the air, "We knew that there were three trapped," said firefighter Bill Shelton. "We didn't know it was children until we got there." Firefighters also would soon learn there were more than three victims.

Doug Dempsey, a volunteer captain at the Seat Pleasant station, recalled that "After they found the fourth, someone said 'When is it going to stop?' It's as shocking as being hit in the face . . . . You feel it that hard."