VANCOUVER -- Police in Surrey are trying to figure out who was setting off homemade explosives earlier this summer.

Witnesses heard several loud bangs and then observed a group of young men leaving a forested area near 4th Avenue and 171 Street in South Surrey on July 19, according to Surrey RCMP.

Numerous reports of similar noises came into police, starting on that date and continuing until Aug. 9. Police did not specify when complaints were made or how many came in.

On that first occasion, officers from the community response unit found "remnants of a small improvised explosive device" where the men were alleged to have been, the RCMP said in a news release.

One of the men is described as white and in his late teens or early 20s. He is said to be 5'10" to 6" tall and roughly 175 lbs with dark, clean-cut hair. He was wearing a white t-shirt, dark shorts and dark shoes. Police say he is known to ride a black mountain bike.

There have been no reports of injuries because of these devices, police say. But they are issuing a warning that no one touch or pick up anything that appears to be an explosive and also leave the remnants of an explosive untouched. They ask the public to call police immediately.

"Homemade devices such as these are dangerous and unpredictable," said Cpl. Bob Keay. "If you're in the area and see a suspicious device, please leave it where it is and give us a call as soon as possible."