Israeli troops searching the West Bank believe three teens kidnapped 10 days ago are still alive, the army’s spokesperson said Sunday.

Israel Defense Forces Spokesman Brig. Gen. Motti Almoz said information collected by the army pointed to Naftali Fraenkel, 16, Gil-ad Shaar, 16, and Eyal Yifrach, 19, still being held alive by Hamas kidnappers.

“The working assumption is that the hostages are still alive and the information that we have allows us to make that assessment,” Almoz said. “We will continue to turn over every stone to get to them — I can’t go into every detail about the operation — but of course the searches are continuing at the moment and we are reviewing how to continue based on conditions on the ground.”

On Saturday, forces shifted their searches to caves, wells and cisterns in the Hebron area, bringing in firefighting units to aid n the operation.

IDF combat engineers reported Sunday they had uncovered dozens of tunnels hidden beneath homes in the West Bank during the quest.

The Yahalom special unit discovered subterranean passageways concealed behind household items such as washing machines or underneath furniture in buildings all over the West Bank, the Ynet news website reported.

The three kidnapped Israeli teens, from L-R: Eyal Yifrach, 19, Naftali Frankel, 16, and Gil-ad Shaar, 16. (photo credit: courtesy)

The three kidnapped Israeli teens, from L-R: Eyal Yifrach, 19, Naftali Fraenkel, 16, and Gil-ad Shaar, 16. (photo credit: courtesy)

Earlier Sunday, Israeli troops recovered a remote control drone that crashed in Hebron while being utilized in search efforts.

The Skylark mini UAV was damaged after plummeting onto a roof in the Ein Sahara neighborhood of the town.

Palestinian police retrieved the smashed vehicle and returned the pieces to the IDF, Israeli media reported. An investigation was launched into what caused the flight failure.

The Skylark UAV is a hand-launched drone used by troops in the field to obtain real-time video of their surrounding region.

An Israeli soldier holds a Skylark drone during the search for three Jewish teenagers near Hebron, in the West Bank, June 14, 2014. (photo credit: Yonatan Sindel/Flash90)

An Israeli soldier holds a Skylark drone during the search for three Jewish teenagers near Hebron, in the West Bank, June 14, 2014. (photo credit: Yonatan Sindel/Flash90)

Various UAVs have been deployed over the past week as part of the intensive search to locate the whereabouts of three kidnapped Israeli teenagers who disappeared earlier this month from a hitchhiking post in the West Bank.

The aerial surveillance has supported a large-scale military operation involving thousands of soldiers and security personnel conducting an inch-by-inch hunt for the teens, who were abducted on June 12.

During the search, troops found more than 10 weapons factories, some of which where hidden inside residential buildings, and seized dozens of grenades and improvised explosives, the military said.

Hundreds of Hamas members have been arrested during the operation. Prime Minister Benjamin Netanyahu has repeatedly accused the terror organization of being behind the kidnappings.