Another child has died in an outbreak of a viral illness at a New Jersey rehabilitation facility bringing the death toll to seven, while 11 others remain sickened, health officials said Wednesday.

Wanaque Center for Nursing and Rehabilitation in Haskell was ordered to stop admitting new patients until the outbreak of adenovirus 7 ends. Health officials confirmed Tuesday that 18 patients have contracted the virus.

"The New Jersey Department of Health learned last night [Tuesday] that unfortunately, another child who was hospitalized due to adenovirus passed away yesterday," New Jersey Health Department said Wednesday. "The young child's death was associated with the 12 confirmed cases of adenovirus among medically fragile children at the Wanaque Center for Nursing and Rehabilitation."

Adenovirus 7 is most commonly associated with acute respiratory disease and can occur at any time throughout the year, according to the Centers for Disease Control and Prevention (CDC).

6 KIDS DEAD, 12 SICKENED IN VIRAL OUTBREAK AT NEW JERSEY PEDIATRIC CENTER

Adenoviruses can cause a wide range of illnesses, including the common cold, sore throat, bronchitis, pneumonia, diarrhea, pink eye, fever, bladder infection, inflammation of the stomach or neurologic diseases. While they typically cause mild illnesses, people with weakened immune systems or existing respiratory or cardiac disease are at higher risk of developing a severe illness.

The outbreak at the New Jersey facility is affecting “medically fragile children with severely compromised immune systems,” the state department said in a statement. Wanaque Center for Nursing and Rehabilitation is a 227-bed facility that received a “below average” rating in its 2017 health inspection report, NJ.com reported. The report stated the facility “failed to ensure infection control practices were followed.”

Officials inspected the facility on Sunday and Tuesday and discovered minor handwashing deficiencies. The health department was first notified of cases of respiratory illness on Oct. 9.

Paula Costigan, whose 14-year-old son was sickened by the virus at the medical facility, told NJ.com she didn't know about the outbreak until a week later.

"He is in really bad shape ... it started to affect his right lung," Costigan said, adding that her son remains in "very serious condition."

New Jersey Gov. Phil Murphy said in a statement Tuesday he was “heartbroken” by the news of the deadly outbreak.

“I am heartbroken by the news that several children have lost their lives in an adenovirus outbreak at the Wanaque Center for Nursing and Rehabilitation, and pray for the full recovery of the other children impacted,” Murphy said in a statement.

It’s unclear what caused the viral outbreak, which is being investigated by the CDC.

Fox News' Alexandria Hein contributed to this report.