The flying formation of four aircraft out for a spin on a rare sunny day in the Fraser Valley came tragically apart Wednesday afternoon when two of the planes clipped wings and spiralled to the ground.

One aircraft recovered, landing in a field, but the second crashed into a slough near the town of Deroche, killing the pilot and a passenger on board.

Sgt. Miriam Dickson of the Mission RCMP said the passenger died at the scene and the pilot was pronounced dead after being airlifted to Royal Columbian Hospital. The names of the victims have not been released but police say they were both men in their 50s.

Clayton Kummel watched the crash while driving home from work.

"I saw two planes spiralling down," said Kummel, a licensed pilot who parked his car and rushed through the knee-deep freezing water of the slough toward the wreckage.

"I called the police as I was wading across. The passenger was already under water and the pilot's head was leaning onto the passengers arm and he was kind of gurgling half in the water," Kummel said in an interview with The Canadian Press.

"I pulled the pilot's head up straight and I pulled the (passenger's) head out the water. I tried talking to them but they were unconscious. Finally another guy came over."

The passenger was not bloodied, but the pilot had a gash on the head, said Kummel.

"We were trying to get the pilot out and then I held the seatbelt around the passenger's head so it wouldn't fall in the water.

"The water was too deep to drag him to shore," he said.

Within less than five minutes, rescue crew and paramedics were on the scene, and Kummel said he watched as the two men were pulled out onto stretchers.

Rick Dekker, of the North Fraser Volunteer Fire Department, said his unit were called to the scene in the Mission area, about an hour's drive east of Vancouver.

Dekker said he lives not far from the scene, and one of his neighbours who saw the planes overhead called him to report the crash.

"Four light aircraft were flying through the sunny skies, two of them made contact," Dekker said in an interview.

"He saw four flying over, he saw contact, he saw one go down."

Dekker said the second person in the plane that crashed into the water was unconscious when the fire department arrived.

The person regained consciousness and was flown to hospital, where he was later pronounced dead.

Bill Yearwood of the Transportation Safety Board said two investigators with the agency were on the scene, but he had few other details.

Do you have photographs or video of the crash that you'd like to share? Email bcassign@ctv.ca.