Dozens were killed and many more were injured when a stampede erupted during ultra-orthodox Jewish celebration early Friday in northern Israel, authorities said.

Israel’s national emergency medical service Magen David Adom (MDA) said at least 38 people were in critical condition and still on Mount Meron where the stampede occurred as at least six helicopters have been dispatched alongside hundreds ambulances to evacuate victims to local hospitals.

The service said another six people in critical condition have been evacuated from the site, adding 18 others have been severely injured, 38 minorly injured and two moderately.

“MDA is fighting for the lives of dozens wounded, and will not give up until the last victim is evacuated,” the emergency medical service tweeted.

Local news organizations  reported the death toll exceeded 40 people.

Video from MDA showed dozens of ambulances waiting to evacuate patients from the mountain in Galilee where tens of thousands had congregated for the ultra-Orthodox Jewish Lag B’Omer holiday despite the coronavirus pandemic.

MDA had originally reported a collapsed bleacher at the site as the cause of the mass casualty event, which it later corrected to a stampede that occurred at around midnight.

Prime Minister Benjamin Netanyahu described it as a “heavy disaster.”

“We are all praying for the recovery of the injured,” he said. “I ask to strengthen the rescue forces operating in the area.”