The fire followed a familiar pattern: It happened early in the morning while the family was sleeping.

Flames, smoke, screams, confusion. By the time the panic had ended, a little girl was dead and three other family members were critically injured.

Later, searchers sifting through the debris in the basement found a new smoke dector -- still in his box.

"Evidence is mounting that smoke detectors save lives and property," the U.S. Fire Administration reported in a recent study. "The risk of dying in a home where dectors are not installed is almost twice the risk in homes where detectors are installed."

"There is unprecedented interest now, partially because of these fires in Las Vegas," said King Harris, chairman of First Alert, a division of the Pittway Corp., the country's largest producer of smoke alarms. "Estimates are that there are 50 million detectors installed in the country. While that sounds good, the typical home has only one detector. If you want to protect a home, you have to have a detector at every inhabitable level of the home or you don't have adquate fire protection."

If a fire begins at night in the basement or on the first floor of a home, it may be out of control before smoke reaches the second floor. You can get additional protection by installing a detector in a bedroom, in addition to installing one in the hall outside the bedroom.

In apartment buildings, units should be placed in common hallways on each floor, and inside the apartments, Harris said. They should be loud enough to be heard inside the apartments and, ideally, should be interconnected so that they are all tripped by any one unit.

Marion Cole, spokeswoman for the National Fire Protection Association in Boston, also recommends that people work out a specific plan for evanucating their home when they hear the alarm. The plan, if possible, also should include alternative escape routes in case a stairway is cut off by flames. The alarm also should be tested so that each member of the household will be able to recognize the device's sound.

There are two basic types of detectors -- photoelectric and ionization. The photelectric is quicker to detect the slow, smoldering type of fire most common in homes. The ionization variety is quicker for blazing fires. There is a third, more expensive variety that combines both methods. The Consumers Union of the United States, which publishes Consumer Reports, suggests using one of each variety or the combination model.

Some other suggestions for detector purchase and use include:

Buy a unit that has been tested by a licensed testing lab, such as Underwriters Laboratories.

A seond-floor detector ideally should be placed in a central hall outside the main bedroom. The first floor detector should be near the foot of the stairs leading to the second floor.

Mount detectors in the middle of a ceiling, if possible. If a detector must be placed on a wall, it should be no more than 6 to 12 inches from the ceiling and not in a corner.

Do not place a detector in a drafty area or near a furnace, shower or kitchen.

Follow the manufacturer's suggestions for testing and maintenance. But change the battery at least once a year, if the unit uses one. Blow some smoke into the detector occasionally to make certain that it is working.

A packet of reading material on smoke detectors can be ordered by sending 25 cents to Smoke Detector Kit, National Fire Protection Association, 470 Atlantic, Boston 02210.