Bill Johnson, Progress's president and chief executive, said Turton was "a valued employee whose insight and hard work had been critical on so many of our legislative and regulatory issues. She was also a dear friend to many of us."

Pete Piringer, a D.C. fire department spokesman, said neighbors called for help about 4:50 a.m. after they saw smoke and flames. The SUV was pointing into the garage at a crooked angle with its back end slightly outside.

Authorities said an autopsy might determine whether the incident occurred after Turton suffered "a medical event," one official said.

Emphasizing that investigators had not determined the facts, the official said Turton might have lost control of the SUV, resulting in a low-speed crash that could have ignited flammable substances stored in the garage.

Neighbors described hearing a crash followed by several popping sounds. They said the fire burned quickly. Julie Domenick, who lives two doors away from the Turton home, said she called 911 after her barking dog alerted her to the fire.

Several parents in the neighborhood said their children sometimes play with the three Turton children, a 21-month-old girl and twin 4-year-old boys.

Harry Lowe, 88, who lives next door to the family, said Ashley Turton was a good neighbor, always concerned about how Lowe was getting along and making sure that the sidewalk in front of his house was cleared after snowfalls.

"It really is such a tragedy for such a wonderful family," Lowe said.

dugganp@washpost.com labbet@washpost.com

Staff writer Anne Kornblut contributed to this report.