Israel said its forces were operating in and around Gaza’s biggest hospital, a chief objective in its campaign to destroy Palestinian Hamas militants that the army says stored weapons and ran a command centre in tunnels beneath the buildings.

Israeli troops forced their way into Al Shifa hospital in the early hours of Wednesday and spent the day deepening their search, the army said. An army video showed automatic weapons, grenades, ammunition and flak jackets it said were recovered from an undisclosed building within the complex.

“The troops continue to search the hospital in a precise, intelligence-based, manner,” army spokesperson Rear Admiral Daniel Hagari said at a press briefing late on Wednesday. “We will continue to do so, in order to gather further information, to discover additional assets, and to expose the terror activities within the hospital.”

U.S. President Joe Biden said that Hamas was committing war crimes by having its military headquarters under the hospital. He said Israel had gone into Al Shifa with a limited number of troops with guns.

“They were told... we discussed the need for them to be incredibly careful,” Biden told reporters on Wednesday.

The Israeli military made no mention of finding any tunnel entrances in Al Shifa. It previously said Hamas had built a network of tunnels under the hospital. Hamas has denied it and dismissed the latest army statements.

“The occupation forces are still lying ... as they brought some weapons, clothes and tools and placed them in the hospital in a scandalous manner,” Qatar-based Hamas senior member Ezzat El Rashq said.

“We have repeatedly called for a committee from the United Nations, the World Health Organisation and the Red Cross to verify the lies of the occupation.”

Israeli forces raided the Shifa complex on Wednesday evening “for the second time in 24 hours” WAFA, the official Palestinian news agency, reported. Bulldozers and military vehicles were used, the agency said, citing local sources.

Hamas-affiliated Shehab news agency reported early on Thursday that Israeli tanks raided Al Shifa from the complex’s southern side and that gunfire was heard in the area.