About 15,000 nurses are involved in the strike, according to New York State Nurses Association.

Thousands of nurses in three hospital systems in New York City went on strike Monday after negotiations through the weekend failed to yield breakthroughs in their contract disputes.

The nurses’ demands vary by hospital, but the major issues include staffing levels and workplace safety. The union says hospitals have given nurses unmanageable workloads.

Nurses also want better security measures in the workplace, citing incidents like a an incident last week, when a man with a sharp object barricaded himself in a Brooklyn hospital room and was then killed by police.

The union also wants limitations on hospitals’ use of artificial intelligence.