Israeli forces say they have arrested around 80 Palestinians in their hunt for three teenagers, who the government believes were kidnapped in the West Bank.
Senior Hamas members were among those detained in a series of raids, according to Israeli media.
Fears are growing for the trio who have been missing since late on Thursday when they were reportedly seen trying to hitch-hike home after classes at a religious seminary north of Hebron.
One of the trio, two 16-year-olds and a 19-year-old, is said to be a US citizen.
Israeli Prime Minister Benjamin Netanyahu blames “terrorists”, saying they came from the Palestinian Authority’s territory.
“Our teenagers were kidnapped by a terror organisation with all certainty. There is no doubt about it,” he said.
“They were kidnapped and they were kidnapped by a terror organisation.”
Palestinian officials say they are helping Israelis in the search but the crisis further strains Israeli ties with the Palestinian Authority, already frayed by its power-sharing deal in April with Hamas Islamists who are hostile to Israel.
Without itself claiming responsibility, Hamas praised those behind the suspected kidnapping.
“Security coordination between (Palestinian Prime Minister Rami) Hamdallah’s and Abbas’s security services and the enemy to locate the heroes of the Hebron operation and arrest them is a moral stain,” said Hamas spokesman Fawzi Barhoum.