Cause of massive Metro Vancouver industrial fire can’t be determined: officials

The cause of a massive fire that started at a warehouse and engulfed a wooden trestle in Metro Vancouver in June will never be known, according to officials.

The blaze broke out on June 20 in Richmond and sent black smoke billowing across the region, prompting an air quality advisory and the temporary closure of the Oak Street Bridge.

On Thursday, Richmond Fire Rescue Asst. Deputy Chief Grant Wyenberg said the case has been closed.

"The site and the remaining structures were determined through an engineer’s report to be unsafe. Without access, we cannot accurately determine a cause and origin for this fire," he wrote in a statement to CTV News.

• In pictures: Massive industrial fire in Richmond

The effort to contain the blaze involved multiple fire departments and was complicated by difficulty accessing the site and because the bridge was coated in chemicals. No one was injured.