The main section of the SkyWest plane crashed between two houses, slid through a chain-link fence and came to rest in the middle of a street.

Sister Marilyn Mark, a teacher at St. Francis Xavier, told the Associated Press she had been sitting in her office near the crash site when the accident occurred. ''I thought someone was up shoveling snow on the roof,'' she said. ''Seconds later, I heard a kind of crash. I ran downstairs to see what was going on. That's when I found part of a body.''

About 30 firefighters in nine pieces of equipment converged quickly on the scene, an area of lower middle-class homes. But the authorities said there were no fires to contend with. 'I Heard a Big Boom'

Martin Bee, who lives in Kearns, said he was outdoors when the accident occurred.

''I heard a boom, a big boom.'' he said, ''and I looked up, and there were just parts flying all over. You couldn't tell one thing or another. You couldn't tell what was what. I was just ducking and trying to stay out of the way of things.''

Tom Doyle, the assistant air traffic manager at Salt Lake International Airport, said the SkyWest plane had been about to turn 90 degrees onto its final approach to the runway when the planes collided.

At an evening news conference, Ron Reber, a SkyWest official, said Flight 1834 was arriving at the airport about 30 minutes late, but he said he did not know the reason for the delay.

The Federal Aviation Administration said in Washington that the commuter craft disappeared from the radar scope at the Salt Lake airport at 12:52 P.M. in Salt Lake City. It was about eight miles southwest of the field at the time.