As soon as the smoke detectors buzzed in Milton Corn's Potomac, Md., house at 4:30 a.m. yesterday, Corn smapped awake. He could smell smoke; he woke up his wife Lynn and jumped out of bed. Then he groped in the darkness toward the hall, thinking he and his wife could run down the stairs and escape. But he could not reach the stairs. A curtain of heavy smoke was in the way.

"There was no question in my mind that this was for real and we really had a problem," said Corn, a professor of internal medicine at Georgetown University Medical School. "I thought we'd be overcome by smoke before we could get out, or that we'd be seriously injured from a fall."

Corn returned to his bedroom on the second floor of his two-story brick house at 6 Over Ridge Court. He and his wife were coughing and gagging. Smoke filled their room. They opened the bedroom windows and began yelling for help.

Their neighbors heard their screams. Wearing nightgowns and pajamas, they ran to the Corn's home.

Kathryn Morrison got there first with her stepladdder, then Richard Fennel arrived.

"They [the Corns] were hanging out from their bedroom window," said Morrison. "They were engulfed in smoke. It was very heavy."

Corn lowered his wife out the window to Fennel, who was standing on the stepladder. The ladder tottered beneath them, and Lynn Corn sprained her ankle.But she was safe.

Another neighbor, Robert Morrison, arrived with another ladder, and Corn climbed to safety.

Soon afterward, the fire trucks arrived. Firefighters extinguished the flames, which they said caused about $70,000 damage. The kitchen was gutted, and the rest of the home was covered with smoke. The cause of the fire was an overheated electrical outlet in the kitchen, firefighters said -- but a clock was the only appliance plugged into the outlet, according to the Corns.

Yesterday, Milton Corn sorted out the burned remnants of furniture inside his home. He said he considered himself a lucky man.

"First, because I was wise about choosing a smoke detector," Corn said. "And I was absolutely brillant about choosing my neighbors."