At least 44 people were killed at a massive stampede at a densely packed Jewish pilgrimage site in northern Israel on Friday.

Ultra-Orthodox Jews gather at the gravesite of Rabbi Shimon Bar Yochai at Mount Meron, Israel, April 29, 2021.

Tens of thousands of pilgrims were gathered in Meron at the site of the reputed tomb of Rabbi Shimon Bar Yochai, a second-century Talmudic sage, where mainly ultra-Orthodox Jews mark the Lag BaOmer holiday when the disaster occurred.

Broken glasses are seen at the site where fatalities were reported, Meron, Israel, April 30, 2021.

Closed last year due to coronavirus restrictions, this year's pilgrimage at which bonfires are lit was expected to be a celebratory event in a nation that has largely reopened thanks to a successful vaccination campaign.

An Ultra-Orthodox Jewish rabbi lights up a bonfire, Meron, Israel, April 29, 2021.

It has been "a tragic night," Shimon Lavi, northern Israel's police commander, told Agence France-Presse (AFP), adding his officers did all they could to save lives, helping to ferry the injured to hospital.

But a witness blamed the police. "There is an iron ramp going down from the site of a bonfire... It was very crowded... people had to walk down on this ramp in order to exit," said Shmuel, an 18-year-old at the scene. The police "closed it (the ramp). Then, more people arrived, and more and more... and police wouldn't let them exit, so people started to fall on top of each other," he said.

Initial reports had indicated the carnage began when a section of stadium seating collapsed but rescue workers later tied the casualties to a stampede.

A spokesperson for the Magen David Adom, Israel's rescue service, told AFP "there were 38 dead at the scene but there were more at the hospital."

A source at the northern Ziv hospital, one of several receiving casualties, told AFP it had recorded at least six deaths, taking the overall toll to 44.

The rescue service said it was treating 150 injured, six of them in serious condition.

Ultra-Orthodox Jews look at the scene where fatalities were reported, Meron, Israel, April 30, 2021.

Israelis gather around a bonfire as they celebrate the Jewish holiday of Lag BaOmer, marking the anniversary of the death of Talmudic sage Rabbi Shimon Bar Yochai approximately 1,900 years ago, in the Mediterranean coastal city of Netanya, north of Tel Aviv, Israel, April 29, 2021.

People wait to be evacuated by buses in the northern Israeli town of Meron early on April 30, 2021.

Israeli security officials scuffle with Ultra-Orthodox Jewish youth at the Jewish Orthodox pilgrimage site of Mount Meron, Israel, April 30, 2021.

An injured man looks on as Israeli Health Minister Yuli Edelstein (unseen) visits the wounded at Ziv hospital, Safed, Israel, April 30, 2021.