Crews rescued more than a dozen people — including parents with their children — who had ventured out onto slabs of ice locked in a slowly moving ice jam on the Bow River, department spokeswoman Carol Henke said.
"They were very, very fortunate that nothing bad happened," she said. "It was a potentially deadly situation."
Henke said the recent warm weather has made the ice unstable.
"It's always disconcerting when you see parents putting children in a risky situation. Children, adults, pets all need to stay off the ice," she said.
"It's dangerous and once something bad happens, there's no going back from that. So let's make safe choices."
Several fishermen were also rescued from the Glenmore Reservoir, she said.
Calgary reached a record-setting 17 C on Sunday.