Transit police are trying to track down a witness in their investigation into an explosive device discovered on the SkyTrain tracks in Surrey last week.

The witness, a white man between 30 and 40 years old, is believed to have been at the King George Station at around 1:30 pm. on Friday, Nov. 2.

A device comprised of three propane canisters was discovered on the tracks just east of Scott Road Station about 45 minutes later.

Police issued a statement emphasizing that the man is sought “as a witness only, not as a suspect or person of interest.”

He is described as being average height with an average build, and was wearing dark framed glasses, a short-sleeved white shirt, beige pants and a backpack.

Anyone with information on the witness, or on the person or persons responsible for leaving the explosive on the SkyTrain tracks is asked to call Transit Police at 604-515-8300 or Crime Stoppers at 1-800-222-8477.