At least 20 people, including five journalists, have been killed in Israeli strikes on Nasser Hospital in southern Gaza.
The death toll was confirmed by Palestinian health officials.
The journalists worked for Reuters, Associated Press and Al Jazeera.
They included Mariam Abu Dagga, who freelanced for Associated Press and other agencies, Mohammed Salama, who worked for broadcaster Al Jazeera, Moaz Abu Taha, a freelance journalist who worked with several news organisations, including occasionally contributing to Reuters, and Ahmed Abu Aziz.
Photographer Hatem Khaled, also a Reuters contractor, was injured.
In a statement, Associated Press said that it was "shocked and saddened" to learn of the death of Mariam Dagga, a 33-year-old who freelanced for the agency since the start of the war.
"We are devastated to learn of the death of Reuters contractor Hussam al-Masri and injuries to another of our contractors, Hatem Khaled, in Israeli strikes on the Nasser Hospital in Gaza today," a Reuters spokesperson said.
The Foreign Press Association called for an "immediate explanation" from the Israeli military and prime minister's office.
"We demand an immediate explanation from the Israel Defense Forces and the Israeli prime minister's office. We call on Israel once and for all to halt its abhorrent practice of targeting journalists," the group said in a statement.
The Israeli military confirmed that it carried out a strike in the area and "regrets any harm to uninvolved individuals".
It added that it "acts to mitigate harm to uninvolved individuals as much as possible while maintaining the safety of IDF troops" and "does not target journalists as such".
The Chief of the General Staff has instructed that an initial inquiry into the strikes begins as soon as possible, the statement said.
It did not say who the military was targeting in the strikes.
Prime Minister Benjamin Netanyahu said that "Israel deeply regrets the tragic mishap" at Nassar Hospital.
"Israel values the work of journalists, medical staff, and all civilians.
"Our war is with Hamas terrorists. Our just goals are defeating Hamas and bringing our hostages home," Mr Netanyahu said.
Watch: US President Donald Trump says he is 'not happy' about strike on Gaza hospital
Gaza's Civil Defence spokesman Mahmud Bassal said that an Israeli explosive drone targeted a building at the hospital in Khan Younis, followed by an airstrike as the wounded were being evacuated.
Witnesses said the second strike took place after rescue workers, journalists and other people had rushed to the site of the initial attack.
The Reuters live video feed from the hospital, which was operated by Mr Masri, suddenly shut down at the moment of the initial strike, Reuters footage showed.
Health officials in Gaza named another of the journalists killed as Moaz AbuTaha.
A rescue worker was also among those killed, health officials said.
More than 240 Palestinian journalists have been killed by Israeli fire in Gaza since the war started on 7 October 2023, according to the Palestinian Journalist Syndicate.
Two weeks ago, Israel killed prominent Al Jazeera correspondent Anas Al-Sharif and four other journalists in a strike.
In that attack, Israel acknowledged targeting Mr Sharif and said he worked for the Hamas militant group, which the broadcaster denied.
The war in Gaza was sparked by Hamas's 7 October 2023 attack on Israel, which resulted in the deaths of 1,219 people, mostly civilians, according to an AFP tally based on official figures.
Israel's offensive has killed at least 62,686 Palestinians, most of them civilians, according to figures from the health ministry in Hamas-run Gaza that the United Nations considers reliable.
People 'living in an immense cage' - MSF
Emergency Coordinator for Médecins Sans Frontières (MSF) in Gaza, Jérôme Grimaud, said that people are "living in an immense cage" and that no hospital is safe.
Mr Grimaud said there were over 50 MSF colleagues in various departments of the hospital, which was hit twice, with three of them extremely close to the strike.
Speaking to RTÉ's News at One, Mr Grimaud said: "One staff (member) was slightly injured, but we are extremely lucky."
He said it was the third time the hospital was struck by Israeli missiles.
"We were hit with no warning. There was no chance for anyone to escape or find shelter.
"As we speak, the hospital is facing a mass casualty incident, where a number of wounded are being accommodated. They are now operating and taking care of the mass casualty incident," he said.
He added that it reveals how "unsafe" Gaza is.
"There is absolutely nowhere to go, not even in a hospital in the Gaza Strip, where you would feel that it is okay to be there, that it is safe to be there.
"We need to remind everyone that Gaza is this immense cage where people cannot leave from. They are trapped in the cage and they cannot cross the border to get protection," he said.
"So, they move from one unsafe place to another, including a hospital."
Mr Grimaud said the IDF issued a press release and are going to "explain as they do each and every time that their target of a civilian facility in a hospital was legitimate".
Accreditation AFP/Reuters
