An explosive was thrown at Israeli students visiting Janusz Korczak's orphanage in Warsaw, Poland, Maariv reported.
The explosive was thrown on Wednesday from a neighboring building at students of Arad's Ort School who were touring Poland on their annual trip.
None of the students or staff members were hurt, and both the students' parents and the Education Ministry were informed of the incident.
The security officer accompanying the group informed local police of the incident.
The group left the site immediately, continuing with the rest of their tour.
Maariv quoted Israel's Education Ministry as stating: "During the students' visit...an explosion was heard. Apparently, an explosive was thrown from a nearby window. The students did not suffer any harm, but there is no question that it was thrown intentionally."
"The security detail accompanying the students evacuated the group from the site, and Polish police began investigating the event. After the students were evacuated, their trip continued as scheduled."