Extra police, security and attendants were called in to work at Metro Vancouver’s SkyTrain Saturday following the discovery of an explosive device on a commuter line in Surrey. B.C.

The increased security came after the RCMP detonated an explosive found Friday on the elevated tracks. Hours after locating the first package, police also found a second suspicious object at a station in Burnaby that turned out to be a false alarm. 

Transit police spokesperson Anne Drennan told The Canadian Press that about a dozen detectives will spend Saturday trying to figure out how the device ended up on the tracks.

The first device was spotted by a Surrey passenger on Friday afternoon. The device was lying between two sets of tracks and appeared to be a pipe bomb strapped to three small, empty propane tanks.

Police evacuated the station and then shut down a portion of the line as explosives experts moved in to remove the device.

Drennan said the device was the size of three fire extinguishers. It could have been thrown or placed on the guideway, she said.

Around 7:30 p.m. local time Friday, an attendant at the Metro-town SkyTrain station in Burnaby found another suspicious device. That station was also evacuated and an RCMP bomb disposal unit was called in to investigate.

They determined the item was simply a piece of PVC drainage pipe with metal pieces attached. The Burnaby station reopened after about two hours.

Drennan told CTV News the device found in Surrey appeared to be much more dangerous.

“It’s very concerning,” she said. “We have reason to believe this might actually be a very real pipe bomb.”

Investigators are now poring over surveillance video, looking for clues into how the device made its way onto the tracks, which sit high above ground level.

“It’s just been laid precariously, perhaps even tossed onto the SkyTrain tracks,” Surrey RCMP Cpl. Drew Grainger told reporters.

“Somebody must have brought that up. Someone should have seen them,” he added.

Drennan said authorities are trying to determine what the capacity of the explosive device could have been if it had exploded.

Drennan told The Canadian Press that, according to explosive technicians, the object would not have detonated on its own but may have been electronically or manually set off.

The empty canisters will also be tested for fingerprints and other forensic evidence.

The SkyTrain tracks between Scott Road and Gateway stations were shut down for about three hours as police looked for clues and for other devices. By 5 p.m. local time, authorities had re-opened the line.

-With files from The Canadian Press