Six Palestinians broke out of an Israeli prison Monday through a tunnel dug beneath a sink, triggering a massive manhunt for the group that includes a prominent ex-militant.
The Israel Prison Service said an alert was sounded at roughly 3:00 am (0000 GMT) by locals who spotted "suspicious figures" outside the Gilboa prison in the country's north.
Police, the army and agents from Israel's powerful internal security agency the Shin Bet joined the search effort, officials said. Sniffer dogs were deployed and checkpoints set up in the area surrounding Gilboa.
Israeli media reports said it was possible the escapees had already returned to the West Bank, a territory occupied by Israel since 1967.
The army said its forces were "prepared and deployed" in the West Bank as part of the operation.
In footage that recalled the iconic 1994 prison escape film "The Shawshank Redemption," the IPS released a video that showed agents inspecting a narrow tunnel dug beneath a sink, burrowing deep into the ground.
The jail break occurred hours before Israel begins its High Holiday season, starting with Jewish New Year which begins at sundown.