Cause unknown

The cause of the fire on the James Street Swing Bridge is still unknown and there is no timeline on when answers will come.

Thunder Bay Fire Rescue responded to the blaze shortly after 7 p.m. Tuesday, and the bridge has been closed since that time.

Fire investigator John Montgomery with the Ontario Fire Marshal's office arrived at the bridge site early Thursday morning and by late afternoon he was still working his way through the scene.

"It's still officially under investigation," Montgomery said.

"We've collected some samples and some components from the first scene that we'll be examining later in a little more detail."

Debris samples will be sent to the Centre of Forensic Sciences in Toronto and Montgomery said the timeliness of the results depend on the centre's caseload.

Montgomery said he couldn't comment on the extent of the damage other than to say there was damage to the wooden on top of the bridge and the support structure below, which is also made of wood.

CN police and crew were on scene Thursday along with Thunder Bay Fire Rescue and Thunder Bay Police Service members.

Montgomery said it will be up to CN Rail to determine if the bridge is safe for rail and motor vehicles, but added it was safe to a degree for pedestrian traffic as CN personnel were walking on the bridge Thursday afternoon.

On Wednesday Lindsay Fedchyshyn, CN Rail’s regional manager of public and government affairs, confirmed to CKPR Radio authorities were treating the burned bridge as a crime scene.

The bridge will be released back to CN Rail once the Ontario Fire Marshal's office has completed its investigation.

City police officers are providing scene security during the investigation, and will not be allowing anyone on the bridge in an effort to protect the crime scene.

No injuries were reported as a result of this fire.