Twelve horses had to be put down after a transport trailer carrying dozens of the animals tipped over on Calgary's busy Deerfoot Trail on Friday morning.
The 15-metre trailer, headed to Fort Macleod with 44 horses, tipped onto its side in the centre median on southbound Deerfoot Trail, north of the Seton Boulevard/Cranston Avenue turnoff, said the fire department.
Police said the driver lost control, then overcorrected, shifting the weight of the trailer and causing it to tip over. No other vehicles were involved.
Firefighters used a plasma cutter to remove the rear portion of the truck, and reciprocating saws to cut into the roof to access the horses, which were in three separate chambers.
Some of the horses were able to walk out on their own, but others had to be dragged out using ropes pulled by firefighters and experienced volunteers in a "heart-wrenching sight," said fire department spokesman Jeff Budai.
Eight horses died or had to be euthanized on scene, while an additional four were transported to Okotoks to be put down.
"It's been a lengthy process, obviously very disheartening to see this many horses injured or deceased," said Budai.
Many passersby and nearby residents rushed to the scene to help, including staff from the Spruce Meadows horse jumping facility.
"The horses are obviously in shock. They've been on their side," said Ian Allison, spokesman for Spruce Meadows, who was at the scene.
"The operation has gone incredibly well. It's been a real testament to teamwork of the Calgary fire department and the city police service [and] to think that we sit in a major city that would have the sort of expertise and resources available here on the Deerfoot Trail with just passersby with corral units, horse trailers."
Southbound Deerfoot Trail was reduced to one lane and northbound traffic was shut down for about three hours.
The driver of the transport truck was not injured. On Friday afternoon, police charged Gordon Trach, 53, from Brosseau, Alta., with careless driving, failing to produce insurance, driving with no licence plate on the trailer, failing to notify registry of change of address and operating a vehicle with the wrong class licence.
Alberta Farm Animal Care, a livestock industry group, said the horses were being transported correctly in a single-bed trailer and they did not exceed the load limits.
Bill desBarres from the Horse Welfare Alliance of Canada said the horses were sold on Thursday in Bonnyville, about 600 kilometres northeast of Calgary. Some were on their way to a slaughterhouse, while others were going to feedlots or to new owners, he said.