At least 23 people were reported killed last night when an Air Canada jetliner en route from Dallas-Fort Worth to Toronto caught fire before making an emergency landing at the Greater Cincinnati Airport.

Air Canada Flight 797, a McDonnell Douglas DC9, was carrying 41 passengers and a crew of five. All of those killed were believed to be passengers, according to preliminary reports received by National Transportation Safety Board officials in Washington.

About 18 people suffered smoke inhalation and minor injuries and were taken to Booth Memorial Hospital in suburban Florence, Ky., and St. Elizabeth Medical Center in Edgewood, Ky., hospital officials told the Associated Press.

Federal Aviation Administration officials in Washington received preliminary reports that the fire appeared to have started in the plane's left rear restroom. A surviving passenger, Montreal businessman Raymond Chalifoux, said the passengers had been moved to seats in the front of the plane after smoke was seen pouring from a rear restroom.

Restroom fires have caused at least one major airline disaster and led to the No Smoking rule in lavatories.

"The pilot was very, very good," Chalifoux said. "He made a very good landing. There was no panic at all. No one was sick. We didn't use oxygen because the pilot said oxygen would have fed the fire."

Another passenger, unidentified, told television station WCPO that smoke could be seen coming from one of the bathrooms.

"The stewardess opened the door to the washroom and the smoke came out," he said.

"They tried to calm us down, saying, 'It's okay, there's smoke, but it's been taken care of.' But it seems like the fire was going and going, and then the smoke, even though the door was closed, was coming through."

The pilot radioed the regional air traffic control center in Indianapolis that "I have a fire on board" at about 7:05 p.m. (EDT), FAA officials said. The plane was immediately directed to the Cincinnati airport, which is in Boone County, Ky. Firefighting equipment stood by.

The plane was on the ground within 15 minutes, according to FAA officials, and apparently made a normal landing. But smoke and flames were visible for at least 45 minutes after it touched down, and heavy smoke continued to billow from the aircraft for about three hours. Holes could be seen in the sides and bottom of the fuselage.

A recurring problem in aviation safety is the fact that once aircraft interiors are ignited, the flames are difficult to extinguish. Further, the fumes from the materials used become poisonous in a short period of time.

Most of the fire damage was in the forward part of the fuselage, Dale Keith, director of operations at the airport, told the Associated Press. That is where passenger Chalifoux said most of the passengers had been moved and where another passenger said most of the casualties occurred.

Rick Kirsch of DeSoto, Tex., whose wife, Connie, was treated for smoke inhalation, said, "I took her to the airport and put her on the plane. She almost sat in the front but decided to sit in the back, and thank God. She said the fire was in the front and that's where they all got killed.

"I'm just going through hell still, even though I know she's all right," Kirsch said. "My mind's just swirling."

Bob Rowel, the supervisor of the River Queen Restaurant, which overlooks the runway, said he saw "billows of smoke leaving the underside of the aircraft and the tail portion of the aircraft. It engulfed the entire plane."

Chalifoux said he never saw flames inside the plane, but as the survivors left the aircraft, firemen told them to get as far away as possible because of the blaze.

A temporary morgue was set up at the airport, which was closed for about three hours to all air traffic. Passengers who were evacuated from the plane were kept isolated.

The McDonnell Douglas DC9 is a two-engine jet that entered service in 1965. It was not immediately known which model was involved in last night's accident.

Experts from the safety board and the FAA flew to Cincinnati last night to begin their investigation.

The fire bore a close resemblance to an accident in Riyadh, Saudi Arabia, on Aug. 19, 1980, when a Lockheed L1011 landed after its crew reported a fire. The landing appeared normal, but no attempt was made to open the doors of the plane after it taxied to a halt, and by the time the fire was extinguished, all 301 people on board were dead.

The source of that fire was never officially determined, but most evidence pointed to ignition in a cargo bay. Autopsies showed that most of the victims died of carbon monoxide inhalation, not from the fire.