Dozens more wounded people were taken to six different hospitals, the health ministry said Friday morning.
A spokesman for the Magen David Adom rescue services called it an "inconceivable catastrophe."
Thousands of worshippers had been celebrating the Jewish holiday of Lag Baomer in the town of Meron, and earlier videos on social media showed people singing, dancing and jumping.
Authorities had capped the number of people allowed at 10,000, but media reports indicated up to ten times that number may have travelled there.
Police have launched an investigation into what happened.
"It was a terrible, tragic night," police chief Shimon Lavi told reporters Friday morning.
Lavi said security forces had prepared thoroughly for the celebration. "Security came first," he said.
He said many police officers had saved lives while putting themselves in danger, and warned against misinformation on social media, adding that he was he was "ready for any test."
"I bear the overarching responsibility for better or for worse," Lavi said.
Chaos
Reports suggest the stampede began when people started to slide on a sloping ramp with a metal floor and corrugated metal partitions on both sides, causing the densely packed revellers to fall over each other. Earlier reports said a stand had collapsed at the gathering.
Witnesses have accused the police of allowing people into a cordoned-off area even though it was already extremely crowded and of not opening the exits on either side quickly enough after people started panicking.
A spokesman for the Zaka rescue services said during the night that the scene was chaotic and many children had been separated from their parents, in comments to Israeli television.
Efforts are being made to reunite the families. "I have worked in the rescue service for more than 20 years, and I have never seen anything like this," he said. "These are unbelievable numbers."
Israeli President Reuven Rivlin wrote on Twitter that he was following the reports from Meron and praying for the recovery of the injured, while Prime Minister Benjamin Netanyahu expressed dismay at the "grave disaster."
Lag Baomer is in part a commemoration of the Jewish uprising against Roman occupiers that started in the year 132 under rebel leader Bar Kokhba.
The burial place of Rabbi Shimon bar Yochai, who was involved in the uprising, is a pilgrimage site on Mount Meron that thousands visit every year on the holiday.
Lag Baomer is also said to be the date that an epidemic that killed many Jewish religious students ended.
Bonfires are traditionally lit on the holiday.
Last year, celebrations were severely restricted due to the coronavirus pandemic.
