Trooper Barry Janney of the Maryland State Police was enjoying an off-duty drink at the first-floor bar of the College Park Holiday Inn late Thursday night when, over the blare of the juke box and chatter of a full house of customers, he heards screams of "Fire!" from the direction of the kitchen.

Fifteen minutes later, firefighters were attacking a blaze consuming a room and hallway in the four-story inn. Janney's chest and nasal hairs were scorced by the flames and smoke eventually made him black out, but, before that, he had helped evacuate 250 panicky hotel guests and late night diners, many of whom had at first thought the alarm bell was a prank.

"There are a lot of people who could have ended up dead," said Anne Patton, assistant innkeeper. "I'd like to send him a get-well card. It was a fantastic thing to do."

Janney, 23, a highway patrolman who joined the Maryland police two years ago, and Prince George's County firefighter Raymond Fletcher, where treated at Greater Laurel-Beltsville Hospital for smoke inhalation and were listed in good condition last night. Two other persons were treated at the scene for superficial wounds.

With memories fresh of devastating hotel fires in Los Vegas and New York that killed more than 100 people, county fire department officials were pleased that their fire was controlled quickly -- in 19 minutes according to official records -- and without serious injury or loss of life.

Investigators are treating the fire as a criminal case, apparently because of suspicions of arson. One Holiday Inn employe said the fire began in Room 122, occupied by a single man. Shortly after he checked in at 11:01 p.m., sounds of objects being smashed were heard from inside. By the time firefighters received the alarm at 52 minutes after midnight, he had disappeared, the employes said.

Sgt. William Johnston of the county fire department said the brick building fully met fire safety requirements. Each room was equipped with a smoke detector. There was a functioning alarm for the entire building and water outlets on upper floors for fire hoses. There were no sprinklers in the building but they are not required under county fire regulations.

When he first heard shouts of "Fire!" Janney decided to take immediate action. "I'm a police officer and I thought I'd have a better chance of getting people to move than others," he said from his hospital room yesterday. A former professional baseball player in the Philadelphia Phillies organization, the 220-pound policeman packed an authoritative figure. He raced from table to table but found many people convinced it was a false alarm and reluctant to get up. "I almost had to pick them up and carry them out," he said.

With some minor panic -- several young women were stepped on in the rush to get out -- the restaurant was cleared in five or six minutes. Janney then turned his attention to the door of a stairwell leading up into the motel. Smoke was already thick. He pounded on the door and screamed upward for people to leave. One by one, dazed guests stumbled down the stairs while others left through exits elsewhere in the building.

The restauant's night manager, Rick Humbert, and a Prince George's County policeman who is an assistant manager there at night, Rex Foster, managed to get into the motel's corridors and began hammering on the doors, employes recalled.

The first county firefighters arrived six minutes after receiving the alarm.

Janney and four of them passed through the stairwell door crouching and dragging a heavy hose behind them. "If you got off your knees, the smoke would gag you," Janney said.

Drawing close to the fire which had spread from the room to the hallways, Janney was singed and lost consciousness briefly. Firefighters helped him to safety.

Many of the 110 guests evacuated from the motel were taken into another Holiday Inn after the fire was brought under control. One of them, Marjorie Davies of Sacramento, Calif., spent 20 minutes yesterday morning singing praise of Janney and the other men who had roused the guests.

A motel employe said Davies told him she was convinced that "if they hadn't pounded on her door, she'd still be laying there. She thought it was a false alarm."