By Debbi Wilgoren
Washington Post Staff Writer
Wednesday, January 23, 2008 8:49 AM

An apparent gas leak inside a 12-unit apartment building in Northeast Washington early today led to an explosion that left at least three people homeless, a D.C. fire department spokesman said.

No one is believed to have been inside the apartment where the explosion occurred, at about 1:30 a.m., fire department spokesman Alan Etter said. Three people were in their apartments elsewhere in the building and were not injured, Etter said.

The explosion blew out windows and sent window trim, blinds and other debris flying into the 4200 block of Dix Street NE, Etter said. Some of the items hit parked cars, and some landed in tree branches and on the street. One car's windows were shattered by the force of the blast.

"Clearly, this was an incident involving natural gas," Etter said, adding that investigators are still trying to determine the source of the leak and the ignition source. He said a strong smell of gas could be detected on the block after the explosion.

Also this morning, Etter said, a man and a woman in Southeast Washington were sickened by a carbon monoxide leak that may have come from a faulty furnace. The woman, 27 years old, was unconscious when firefighters were called to their home at 430 Mellon St. SE, about 5:30 a.m. The man, 30, was conscious but showing symptoms of carbon monoxide poisoning.

Both revived somewhat after they were taken from their home into the fresh air. They were taken to George Washington University Hospital for treatment.

Etter said the incident, and the explosion across town, should serve as a reminder for people to have their furnaces checked and to be vigilant about possible gas leaks.

Furnaces are "in high-volume usage at this time of year," Etter said. He said D.C. residents can receive combination carbon monoxide-smoke detectors free from any city fire station.

"There's no reason why you shouldn't have one in your house, especially if you can get them for free," he said.