Elven persons were injured yesterday morning when leaking carbon monoxide fumes seeped into their bedrooms from a boiler room in a Southeast Washington apartment building, D.C. fire department officials said.

A water heater in the basement of the East Hamilton apartments, 4736 Benning Rd. SE, emitted the fumes into the air rather than into a chimney flue, which had malfunctioned, fire officials said.

"My wife almost fell out when she stepped from the house this morning," said John Meriweather, who lives in the apartment building. "It was strange. I didn't feel anything unusual."

Firefighters and ambulances began arriving at the complex at 8:30 a.m. after several residents began complaining of nausea and headaches. One woman fainted in a hallway, a neighbor said.

All but five of the 11 injured were released after treatment at D.C. General Hospital, The five who were admitted for observation all are children, according to a spokesperson for D.C. General.

"I couldn't smell anything," said Charles Vinson, 12. "My next door neighbor came by and asked how people were feeling. She said other people had headaches. I was on my way to school and I saw one of my friends in an ambulance."

Fire officials said the building houses about 50 persons. Inspectors said yesterday that the ordorless fumes had dissipated shortly after they arrived.

"It happened during the night, so you couldn't tell anything strange," said Brenda Fisher. "The firemen said it was odorless and could have gotten pretty lethal."

Hospital spokespersons listed the conditions of those admitted as fair.