The Israel Defense Forces released footage Sunday of a tunnel in the city of Khan Younis in southern Gaza where it said Hamas held around 20 hostages at different times. 

The tunnel was located in the center of Khan Younis and ran about 830 meters (0.51 miles) at a depth of 20 meters (66 feet), the IDF said.

There were booby traps, explosives and various obstacles inside the tunnel, according to the IDF, which said it encountered and killed several Hamas operatives as it entered the tunnel.

The IDF found no hostages in the tunnel but said, based on testimonies from former hostages and DNA evidence, that about 20 hostages were held there at different times, some of who have been released while others remain held in Gaza. 

Videos shared by the IDF show long tunnels, some of which lead to rooms with mattresses, blankets and food wrappers scattered on the floor, and kitchen and bathroom areas. 

An estimated 104 hostages are believed to be alive in Gaza, according to the latest Israeli figures, which have fluctuated at times based on intelligence.