Investigators and homicide detectives were still sifting through the rubble over the weekend trying to determine the cause of a raging house fire that killed two teens and injured an adult in Alexandria in the early hours of Friday morning.

Fairfax County fire investigators said the fire broke out at about 12:30 a.m. at 2421 Popkins Lane in Alexandria, and within minutes a half doezen neighbors rushed out of their homes when they heard the girls’ father screaming for help.

“The father was on the roof screaming for the children but there was really nothing he could do,” said Marissa Carpenter, a neighbor. “He was crying and looked badly burned.”
 
Morgan Whitsett, 16, and her 13-year-old sister Ashley perished in the blaze. Morgan attended West Potomac High School, and Ashley attended Carl Sandburg Middle School. Fire officials said they found evidence the girls had tried to get out of the house. The bodies of the two teens were found in an upstairs bedroom. Officials said they had died from smoke inhalation.
 
After firefighters arrived they encountered heavy fire in the front area of the house, which took about 30 minutes to put out. There has been no official cause for the cause the fire, which caused an estimated $200,000 in damages.

“They were sweet, well-behaved girls,” Carpenter added. “A little on the shy side, but model teenagers.”

Neighbors reported that while the girls’ father was trying to get them out of the burning house, a woman who was in the house left and sped off in a car.  “It seemed really strange that someone would just take off in the middle of it all,” Carpenter said.

The victims’ father was treated for burns at Washington Hospital Center and released.
 
The victims are the seventh and eighth fire fatalities in Fairfax County this year, police said.