Croupiers at the Montreal Casino went on a surprise four-hour strike late Saturday afternoon in a show of solidarity amid a negotiations deadlock.

At the stroke of 4 p.m., croupiers laid their cards on the table and walked out the door to demonstrate in front of the Notre Dame Island casino, denouncing the standstill in discussions over their contract.

The collective agreement, which applies to 521 croupiers, expired March 31, with salaries and schedules among the issues at stake.

The strike was slated to continue until 8 p.m. Saturday night, though Loto-Québec, which manages the province’s casinos, says the gaming tables remain open with the exception of the poker room, which shut down temporarily.