Nurses from Twin Cities metro and Duluth-area hospitals went on strike at 7 a.m. Monday, after unsuccessful negotiations on overdue three-year contracts.

Here's what you need to know.

Which hospitals and how many nurses are involved?

About 15,000 nurses are on strike in the Twin Cities metro and Duluth area.

Hospitals involved in the strikes in the M Health Fairview system include Southdale in Edina, St. John's in Maplewood, St. Joseph's in St. Paul and the Riverside campus of the University of Minnesota Medical Center. Allina Health hospitals under strike include Abbott Northwestern in Minneapolis, Mercy campuses in Coon Rapids and Fridley and United Hospital in St. Paul.

Nurses are also on strike at Methodist Hospital in St. Louis Park and North Memorial Health in Robbinsdale. North Memorial is the only one of three major adult trauma centers involved in the strike.

Strikes in the Duluth area include St. Luke's Hospital and Essentia Health's St. Mary's Medical Center in Duluth and Superior, Wis.

Which hospitals are not involved in the strike?

Two of the Twin Cities' three adult regional trauma centers — HCMC in Minneapolis and Regions Hospital in St. Paul — are not involved in the strike.

In addition, several suburban Twin Cities hospitals do not employ union nurses and are not involved. For instance, Allina's Buffalo and Cambridge hospitals are not involved and neither are M Health Fairview's Ridges Hospital in Burnsville or Lakes Medical Center in Wyoming. North Memorial's Maple Grove Hospital also isn't under strike.

How long will the strike last?

The union has said the strike could last three days, starting at 7 a.m. Monday and ending at 7 a.m. Thursday.

Will people be able to get hospital care during the strike?

Hospital leaders say they hope to maintain their usual capacity during the strike, but it depends on how many temporary nurses they can recruit.

Children's Minnesota already announced it is planning only emergency surgeries at its Minneapolis and St. Paul hospitals during the strike. Otherwise, the system anticipates full emergency care at the hospitals and usual outpatient care at its clinics and Minnetonka surgery center.

A statement from Essentia on Wednesday pledged "uninterrupted urgent and emergency care" during the walkout.

Fairview in a statement said that the initial number of temporary nurses looks favorable to maintain operations at the University of Minnesota Medical Center, St. John's in Maplewood, and Southdale in Edina — and at a long-term acute care ward at St. Joseph's in St. Paul.

Hospitals also have been shifting available outpatient clinical staff into appropriate hospital roles. North Memorial in a statement said some nonclinical workers are being repurposed as greeters to help visiting nurses and patients find their ways around the hospital.

Why are the nurses striking?

The nurses, who say they are facing a "crisis of retention," voted to authorize the strike after weeks of unsuccessful negotiations over new three-year contracts.

They've been negotiating on wage increases, staffing levels and compensation and support after two and a half years of pandemic.

Both sides agree on the need to improve recruitment and retention, but the hospitals contend the nurses' proposals are too costly. The nurses are seeking more than 30% increases in compensation by the end of the three-year contract, while the hospitals have offered 10 to 12%.

When was the last nurses strike?

There were two strikes totaling 44 days by Allina nurses in 2016 in a dispute over health benefits. Twin Cities' hospital nurses also went on strike for one day in 2010.