JERUSALEM – An apparent stampede occured at an overcrowded Israeli festival after midnight Thursday, causing dozens of casualties, local media reported.

The tragedy, which happened in northern Israel, left 50 people injured and around 20 in critical condition, and many people are feared dead, the Haaretz daily cited Israeli ambulance service Magen David Adom as estimating.

The specific cause was not immediately clear, and initial reports pointed to a stand collapse at a concert.