Cammalleri made it 3-1 at 10:17 after Montoya failed to control the rebound of a Kempe shot. Montoya tried to knock the puck away with his stick, but Cammalleri backhanded it into an empty net for his second goal of the season after outflanking the goalie.
Kempe scored on a breakaway over a falling Montoya for a 4-1 lead with 3:18 left before completing the hat trick with a one-timer off a Cammalleri pass to make it 5-1 with 1:36 remaining.
"Unnecessary risks, simple as that," Canadiens coach Claude Julien said of their third-period breakdowns. "We have to be a lot better and a lot smarter in those situations if we're going to turn this around and win some hockey games."
Byron put Montreal ahead 1-0 at 10:31 of the first. Phillip Danault took a sharp-angled shot that went off Quick's right leg and into the crease, where a diving Byron smacked it in for his first goal.
Cammalleri scored on the power play to tie it 1-1 with 2:38 left in the first.
After starting the season 0-for-16 on the power play, the Kings have scored on five of nine opportunities over three games.
Los Angeles defenseman Jake Muzzin had an assist to extend his point streak to five games (one goal, four assists), and Kings rookie defenseman Oscar Fantenberg had an assist for the third straight game.
The Canadiens have been held to one goal or fewer in four games. Byron said they would be well-served to copy the example set by the resurgent Kings.
"You see some of the Kings' goals tonight and they're just firing pucks to the net and just getting bodies there, keeping it simple," he said. "I think that's just something we are missing in our game right now."
