The boys, all in their upper teens, were nauseous, vomiting and feverish, among other reactions, after landing at an unidentified New York City airport, responders said.
They apparently had been eating tuna sandwiches before their flight and began feeling ill during the journey, according to unconfirmed reports.
The Vishnitzer Chassidim groups had all traveled together to visit Mezibuz, The Yeshiva World reported.
Rockland Hatzolah set up a command setup at its Monsey garage after at least eight boys were reported sick.
Another boy, from Vishnitz Yeshiva in Kiamisha Lake, NY, also reportedly was hospitalized.
In Brooklyn, 18 boys from Yeshiva Bochrim were dropped off by a school bus at the Boro Park Hatzolah garage on 14th Avenue, where a mass casualty incident was reported, The Yeshiva World reported.
The borough teens were taken to Maimonides, Lutheran, Methodist and Cobble Hill hospitals, responders said.
Click here to follow Daily Voice Saddle Brook-Elmwood Park and receive free news updates.