The Israeli army stormed the Al-Shifa hospital in Gaza City in one of the biggest operations in the north of the strip since the start of the war against Hamas. At least 20 armed Palestinians were killed and dozens of suspects were arrested, the Israeli military said, as quoted by Reuters. The head of Hamas’ internal security was among those killed, according to the Israeli newspaper Haaretz.

“20 terrorists have so far been eliminated at Shifa Hospital in several clashes, and dozens of captured suspects are currently being interrogated,” the Israeli military announced.

The army also says it found weapons and funds belonging to the Hamas group in the hospital.

According to the army, Faaq Mabhuh, head of Hamas’ internal security, was among 20 Palestinians killed in Monday’s operation. He was responsible, among other things, for organizing Hamas operations in the Gaza Strip.

Mabhu was armed and was hiding in one of the rooms in the hospital and there were many weapons in the next room.

Al-Shifa, one of Gaza’s largest hospitals, is one of the few medical facilities still in operation.

Ceasefire talks in the Gaza Strip resumed on Monday, when an Israeli delegation led by the head of the Mossad left for Qatar. The two camps are negotiating a six-week truce, during which 40 hostages will be released in exchange for hundreds of Palestinian prisoners.

Israel said it would only discuss a temporary ceasefire, while Hamas said it would not release the hostages without an agreement to end the war.