TRENTON, N.J. (AP) — Nearly two dozen children at a long-term care facility showed symptoms of a viral infection and two had died by the time New Jersey's health department was notified about the outbreak this fall, said Dr. Shereef Elnahal, the department's top official.

At a hearing Monday on the deaths of 11 children at the facility, Elnahal told a legislative committee that he has formed new internal policy requiring him and his principal deputy to be notified of any outbreaks where pediatric deaths have occurred.

"Leadership at the highest levels in the department need to be made aware of severe facility outbreaks immediately, in case deviations from protocol are warranted," Elnahal said.

Elnahal also told the legislative oversight committee it's possible "we may never know" how the adenovirus was introduced at the Wanaque Center for Nursing and Rehabilitation in Haskell. The particular strain found at Wanaque can cause serious illness in healthy people, he said.

Representatives of the facility were invited to Monday's hearing but didn't attend.

The children at the facility all had serious underlying health conditions, and many were on ventilators. The first patient showed symptoms of the infection on Sept. 26, and health officials were notified on Oct. 9. By that time, two patients had died and 20 showed symptoms, Elnahal said.

It took facility staff nearly a month to completely separate healthy patients from those who were affected by the virus because of a lack of space, Elnahal said.

That occurred on Nov. 17, and no patients are known to have contracted the virus since then, he said.

Elnahal said his staff found "infection control deficiencies" at the facility during inspections between the end of October and the middle of November.

An attorney who represents the facility didn’t immediately return a message seeking comment.