MINNEAPOLIS (AP) — Thousands of nurses in Minnesota launched a three-day strike Monday over issues of pay and what they say is understaffing that has been worsened by the strains of the coronavirus pandemic.

The labor action includes 15,000 nurses and seven health care systems in the Minneapolis and Duluth areas. Those groups have recruited temporary nurses and say they expect to maintain most services.

Nurses were seeking more than 30% increases in compensation by the end of the three-year contract. Hospitals have offered 10% to 12%.

The Minnesota Nurses Association said that unless benefits are substantially improved, the continued loss of nurses will leave hospitals vulnerable.

“They need to see it as the crisis that it is,” union president Mary Turner said when nurses gave notice in August of their strike plans. “We’ve said over and over that this isn’t something we do lightly but were not going to just sit back and do nothing. We can’t.”

Hospitals have argued that the proposals by the union and its nurses are too costly.

“It just isn’t a realistic number,” Paul Omodt, a spokesman for several of the Minneapolis-area hospitals, said last month.

Union officials say 15 hospitals would be affected by the strike, including those operated by Allina Health, M Health Fairview, Children’s Hospital, North Memorial and HealthPartners. In Duluth, it’s Essentia and St Luke’s.

When Minnesota nurses went on a one-day strike in 2010, hospitals hired 2,800 replacement nurses, called in extra non-union staff and reduced patient levels. Some hospitals rescheduled elective surgeries.