The successful removal of six tanker cars carrying flammable liquids from a broken Calgary bridge is being hailed as a success by the city’s acting fire chief.

Crews removed the cars from a rail bridge in the Bonnybrook industrial area of Calgary early Friday morning, after the cars spent nearly 24 hours teetering over the swollen Bow River.

The cars were drained of their products and pulled off the bridge, with none of the liquid leaking into the river.

The cars derailed early Thursday morning after a structural failure in the bridge caused a portion to buckle as the CP freight train was crossing it. Crews spent most of Thursday preparing to recover the rail cars and the cargo.

Calgary’s acting fire chief Ken Uzeloc praised the crews who removed the cars, calling the entire exercise “very successful.”

Uzeloc said the rail cars were eventually dragged off the bridge by locomotives, after being secured and drained of their products -- which were reported to be flammable.

“We had no injuries, no product (leaked) … I think it was very successful,” he said during a news conference Friday morning.

Around 50 first responders were involved in the operation, he said.

He credited the successful recovery to careful preparation and “taking the time to have a good solid plan.”

He noted that all the first responders, who are still dealing with the fallout of the devastating flooding that hit the city late last week, were ready for a break.

“This sounded like an exercise when I first heard about it,” he said. “I think we’re due for a couple nights of calmness.”

Meanwhile, the Transportation Safety Board of Canada announced that it is launching a formal investigation into the derailment.

Wendy Tadros told Canada AM Friday that despite CP’s claims that it was a failure in the bridge’s piers that caused the derailment, it was too soon to draw any conclusions.

“There’s been an awful lot of speculation out there in the last 24 hours, but I would caution that we just have to follow the evidence,” she said.

Tadros said TSB officials will now begin examining the cars, the bridge and the tracks to gather more information.

CP CEO Hunter Harrison said the bridge break was caused by a failure in the bridge piers at the bottom of the river. Engineers said fast-moving water had scoured the gravel away from underneath the bridge supports, he said.

CP spokesperson Mark Seland said Thursday that the bridge had been inspected 18 times since the flooding began. Earlier in the day, the company said the bridge was last inspected on Saturday, with the tracks last inspected on Monday.

Calgary Mayor Naheed Nenshi slammed CP for the derailment Thursday, and suggested the bridge should have been inspected yet again.

He suggested that recent layoffs at CP may have led to a decrease in bridge inspectors, but CP said the number of bridge inspectors has not changed.

Following a conversation with Harrison, Nenshi said the company had apologized for the chaos the derailment had caused.

Tadros wouldn’t comment on statements made by Nenshi that municipalities often feel powerless over railways which are under federal jurisdiction, but often affect cities and towns.

Nenshi pointed out Thursday that railways are private companies, which has been a point of contention for municipalities that are powerless to regulate them.

Tadros said that in terms of municipalities, “there’s a reasonable expectation that those railways are safe.”

She said there is a regular schedule for inspections set out by Transport Canada and the TSB will be looking to see if the schedule was followed for the Calgary bridge. The TSB investigation will be looking into whether all the required inspections were completed, as well as if the federal safety standards were met.

Tadros could not give a timeline for how long the investigation would take, but said any immediate safety concerns would be communicated to the public.