The FBI has launched an investigation following a spate of hoax calls warning of shootings on university campuses.

Since Thursday, nearly a dozen universities across the US have been targeted by “swatting” hoaxes, triggering armed police responses that have sparked panic as students and staff return from the summer break.

Villanova University, a Catholic college in Pennsylvania, was the subject of two false shooting reports last week, including one that interrupted a Sunday Mass for new students.

Rev Peter M Donohue, the university’s president, condemned the “cruel hoax”, which he said had “shaken our entire community”.