The Telenet-Videa team said Dombroski was hit while she rode behind a scooter in Sainte-Catherine-Waver, VeloNews reported. The driver of the scooter was not hurt.
The truck driver, a 52-year-old man, was determined to be sober, Telenet said.
"It is terrible, terrible news," Corne Lepoeter, president of Telenet's development team, said. "We are all so sad."
Dombroski, 26, was born in Jericho, Vt., and had moved to Boulder, Colo. She was a cyclocross racer and in late September competed in the Gran Prix of Gloucester in Massachusetts.
She was on the U.S. world cyclocross team several times.
Jamey Driscoll, a professional cyclist who was a childhood friend of Drombroski from Vermont, called her "an awesome person to have in the sport."
"She was always charismatic, but she was much more outgoing when she was cycling," he said. "She was personable and talkative. It didn't really matter who you were, or whatever. She was just as happy to see me, who she's known for a very long time, as someone she'd just met and was into cycling at a bike race. And that's really cool."