Six children have died from an adenovirus outbreak at a nursing and rehabilitation facility in New Jersey.

The New Jersey Department of Health confirmed 18 cases of adenovirus among pediatric residents at the Wanaque Center for Nursing and Rehabilitation in Haskell and that six had died.

A statement from the state health agency said a team found "minor handwashing deficiencies" at the facility on Sunday and that it engaged in an ongoing outbreak investigation.

The department said the facility cooperating and not admitting any new patients until the the outbreak ends.

Adenoviruses are "a family of viruses that often cause mild illness, particularly in young children," the department said. "Unfortunately, the particular strain of adenovirus (#7) in this outbreak is affecting medically fragile children with severely compromised immune systems. The strain has been particularly associated with disease in communal living arrangements and can be more severe."