BURLINGTON, Vt. (AP) — A union says 1,800 nurses at Vermont’s largest medical center are on strike following unsuccessful contract negotiations.

The Vermont Federation of Nurses and Health Professionals and UVM Medical Center met again Wednesday, but were not able to reach an agreement. Nurses were on picket lines as of 7 a.m. Thursday. The strike is to last through 7 a.m. Saturday.

UVM Medical Center President Eileen Whalen said the center is disappointed the union didn’t change its position. She said UVM increased its offer to a 14 percent pay increase over three years. The union countered with 22 percent over the same period.

The union maintained that higher wages are necessary to recruit and retain nurses and support staff and “address a crisis of understaffing.”

Hospital officials have hired temporary nurses to continue providing care.