Two young sisters were killed and their father was seriously injured yesterday in a smoky two-alarm fire that blazed through their third-floor apartment in the Wheaton area, Montgomery County fire officials said.

Suzane Andraos, who was about 2 1/2 years old, and her 13-month-old sister, Joyce, died after firefighters pulled them unconscious from the smoke and flames that engulfed their apartment in the 3800 block of Bel Pre Road about 4:30 p.m., a county fire department spokesman said.

The children's father, identified by the spokesman as Saad Andraos, was taken to the burn unit at Washington Hospital Center, where he was listed in serious but stable condition last night.

The children's mother was not in the apartment when the fire occurred.

The cause of the blaze remained under investigation last night, said Capt. Ray Mulhall, the fire department spokesman. He said it caused $141,000 in damage and forced the evacuation of 14 nearby apartments.

Witnesses told of seeing flames leaping from the windows of the burning apartment. Billowing clouds of smoke apparently thwarted efforts by the children's father and at least one neighbor to rescue the girls.

The neighbor, who declined to give his name, said that after being alerted by a hallway smoke detector, he opened the door of his apartment to find the distraught father in the hall.

"The man kept saying, 'My babies are in there; my babies are in there,' " the neighbor said.

The door of the family's apartment apparently had locked behind Saad Andraos, according to the neighbor.

The neighbor said he threw his shoulder against the door and forced it open, only to be repelled by smoke and flames.

Firefighters were called about 4:20 p.m., Mulhall said. The first to arrive came from Station 25 of the Kensington Volunteer Fire Department, and they immediately set out to find the trapped children, Mulhall said.

Wearing breathing apparatus, they entered the blazing apartment and located the children on the floor of a hallway in the rear of the unit, he said.

A neighbor said he watched as the firefighters carried the children out. "The kids were limp," he said.

While the firefighters who had found the children began administering cardiopulmonary resuscitation, reinforcements arrived to battle the blaze, Mulhall said.

Meanwhile, choking smoke from the burning apartment filled the third-floor hallway.

The neighbor who had tried to enter the apartment retreated to the balcony of his own unit with his roommate.

Neighbors stood below, shouting advice. The two were later led to safety by firefighters, Mulhall said.

The children were flown by Maryland State Police helicopter to Children's Hospital in the District. The older child was pronounced dead at 5:17 p.m. and her sister three minutes later, a hospital spokeswoman said.

Many residents of the condominium development were grieving for the children last night.

"It was terrible," said one woman who watched the swirling smoke from the window of her own unit. "Those two little children! . . . It was horrid."

"We saw them carrying out the children," another neighbor, Alfreda Wallace, said sadly. "They were cute kids."

Wallace was among the residents of the three-story building who was allowed to return briefly to her apartment to collect belongings before the structure was evacuated.

Authorities said residents of most of the units indicated that they would spend last night with friends; others were to be housed by the Red Cross.

One neighbor said the Andraos family rented their unit from a relative and had lived at the development for about two years.

As the evacuated residents left the building last night, a pile of debris flung from the burning apartment lay nearby. It included a stuffed dog, a diaper and a baby bottle.

Staff writer Retha Hill contributed to this report.