WHITEFISH, Mont., Jan. 22— People in this mountainous resort town of 4,600 people were grieving today for nine people who were killed when a school bus carrying a high school wrestling team collided with a fuel tanker in a snowstorm.

''A little bit of all of us died yesterday,'' said Mayor James Putnam. ''The people of Whitefish are in shock. I'm sure that Jan. 21 will remain in the minds of Whitefish people for many, many years as one of the most tragic things that ever happened to us.''

The crash Saturday night also injured 19 people. Only one remained hospitalized Sunday, according to the Flathead County sheriff's office.

The bus, carrying about 30 wrestlers, coaches, cheerleaders and others from Whitefish High School, was returning in defeat from a match at Browning, 94 miles to the northeast. It collided with the empty fuel tanker truck on U.S. 2 and burst into flames.

The bus struck the double-tanker rig, which had jackknifed across the highway, at about 6:30 P.M. some 22 miles southeast of West Glacier.

State's Worst Accident

Al Goke, state highway traffic director, said it was the worst traffic accident recorded in Montana. He said the National Transportation Safety Board would investigate.

The injured included the truck driver, Harold Belcher, 63 years old, of Cut Bank, said Corky Derby, a sheriff's spokesman. She said the dead included the bus driver. Identities of most victims were not being released until Monday because of problems locating relatives.

In Browning, school Superintendent Pat Conroy said the local athletic booster club was meeting today to draft a letter to the Montana High School Association asking that the district be reclassified to another conference so its teams no longer have to travel west across the Continental Divide.

''It's awful we have to have a tragedy like this to show what the problem is,'' he said.

Other Team Accidents

In another accident, a bus carrying the Western Montana College basketball team from Dillon crashed head-on today with a truck near Silver Star, about 170 miles southeast of Whitefish.

The truck driver was killed and the bus driver was injured, but players and coaches received only bruises and cuts.

In a crash in southeastern Washington on Saturday, a member of the University of Oregon wrestling team was killed and eight people were injured, three hospitalized in critical condition. In that accident, a van carrying 10 wrestlers and two coaches went over a guard rail and 185 feet down an embankment, 18 miles west of Pomeroy.

The most seriously injured survivor was the son of Ken Kesey, author of ''One Flew Over the Cuckoo's Nest.'' The young wrestler, Jed Kesey, was in ''very critical'' condition today at Deaconness Hospital in Spokane. The dead student was identified as Lorenzo West, 20, of Portland.

The team had been on its way to a match against Washington State University.