MONTREAL -- The CHSLD Sainte-Croix long-term care home in Marieville, Quebec about 40 minutes south of Montreal was spared from COVID-19's devastating toll on seniors' centres in the first wave of the pandemic.

During the second wave, however, the story has not been the same.

According to the workers' union, 13 patients have died, 37 others have tested positive, and 45 staff members have caught the virus.

The union wants to know what happened.

"We've already been promised there will be an internal investigation to find out how it's possible we had such a serious outbreak," said the nurses' union's president Denis Grondin.

The home is for people who are not autonomous, so one theory is that an employee brought the virus in.

"Someone could have been doing groceries on the weekend, caught it, had no symptoms and then infected people here when they were back at work on Monday," said Grondin. "We know how fast it spreads."

The issue now is staffing.

Many remaining staff members have had to work overtime to ensure there's adequate care with so many staff off.

"Staff is already exhausted," said Grondin. "They had a hard time in the first wave, and many didn't get summer vacations to rest. I have nurses breaking down. You can't imagine what they're going through."