Two outdoor graduation ceremonies in Paterson, New Jersey, held during a dangerous heatwave ended with more than 100 people receiving treatment and some being taken to the hospital, authorities said.

The mayor said about two dozen people were treated for heat-related illness during the ceremony for JFK High School. Four of them were taken to the hospital.

A sweltering heat wave turned what should have been a joyous celebration for Paterson’s graduating seniors into a medical emergency on Monday,