The killings were carried out by undercover operatives while the men were sleeping at Ibn Sina Hospital, according to statements issued by the Palestinian Ministry of Health and the Israeli army on Tuesday.

“This morning three young men were martyred by the bullets of the occupation [Israeli] forces who stormed the Ibn Sina Hospital in Jenin and shot them,” the Ministry of Health in Ramallah said.

The Israeli army said its troops had “neutralised” the men, who were hiding in the hospital and belonged to a “Hamas terrorist cell”.

Security camera footage circulated online appeared to show about a dozen undercover personnel, including three in women’s clothing and two dressed as medical staff, pacing through a corridor of the hospital with assault rifles.

The Israeli military identified one of the men killed as Mohammad Jalamneh, 27, who it claimed was planning an imminent attack and had been transferring weapons and ammunition to other members.

The two other men killed, brothers Basil and Mohammad Ghazawi, were hiding inside the hospital and were involved in attacks, the military alleged.

“A gun was found on a wanted person, which was confiscated by the forces,” the army statement added.

Al Jazeera’s Charles Stratford, reporting from Ramallah in the occupied West Bank, said: “One can only imagine the terror of the patients and staff at the hospital in Jenin.”

“It’s just another example of how determined the Israeli army is to keep up raids as it targets armed resistance fighters across the occupied Palestinian territory,” he added.

Hamas said in a statement that the Israeli army’s “crimes will not go unanswered”, adding that the killings are a “continuation of the occupation’s ongoing crimes against our people from Gaza to Jenin”.

One of the men was injured and in bed when he was killed, said the Palestinian armed group.

Hamas confirmed that Jalamneh was one of its members. The Jenin Brigade, which includes a number of Palestinian armed resistance groups, said in a statement that two of the three men were members of Islamic Jihad.

Basil was injured by missile fragments following an Israeli drone attack on October 25 targeting a group of men near the Jenin camp cemetery and had been receiving treatment at the hospital for three months, according to Al Jazeera sources.

The Palestinian Ministry of Foreign Affairs condemned “in the strongest terms the occupation forces’ assassination of the three young men”.

Crowds thronged the streets of Jenin as the funeral ceremony for the three men was underway. They were to be buried at a cemetery in the Jenin refugee camp.

The mother of the Ghazawi brothers said the two were loved by everyone. “The last time I saw them was yesterday night … I was in the hospital,” she said in a video shot by local media, adding that she went home as Mohammad said he would stay with Basil.

“I was still waking up this morning when I heard that special forces raided the hospital … They were killed while they were asleep.”

‘Undercover assassins’

According to the medical staff one of the three Palestinians killed in the hospital was being treated for an injury received during a previous army raid months ago, Al Jazeera’s Stratford reported.

“The Israeli army often surrounds and in some instances has attacked the three Palestinian hospitals in Jenin during nightly raids on the city,” he said.

“But this is the first time they have entered a civilian medical facility in what seems to have been a well-planned, targeted assassination operation that Palestinian authorities are calling another violation of international law,” he added.

Al Jazeera’s Rory Challands, reporting from occupied East Jerusalem, said that assailants were dressed as doctors, nurses and even civilians.

“This unit comprised Israeli police and army personnel. They went up to the third floor of the hospital and shot three young Palestinians dead,” he said.

“It does not look like there was any attempt to arrest these men. They were killed as they were sleeping,” he added.

Violent clashes were reported in the area surrounding the hospital.

Since the beginning of Israel’s war on Gaza, Israeli forces have carried out raids and arrests in the occupied West Bank on a daily basis.

Hundreds of people have been killed and arrested since Hamas’s October 7 attacks on Israel, in which about 1,140 people were killed and some 240 taken captive.

Approximately 100 of the captives were returned to Israel under a truce deal last November in exchange for the release of Palestinian prisoners in Israeli jails.

At least 26,637 people have been killed and 65,387 wounded in Israeli attacks on Gaza.