Israel struck one of the main hospitals in the Gaza Strip on Monday and then hit the facility again as journalists and rescue workers rushed to the scene, killing at least 20 people and wounding scores more, local health workers said.

It was among the deadliest of multiple Israeli strikes that have hit both hospitals and journalists over the course of the 22-month war. The assault came as Israel plans to widen its offensive to heavily populated areas, vowing to destroy Hamas after its Oct. 7, 2023, attack.

Among the dead were five journalists, including 33-year-old Mariam Dagga, a visual journalist who worked for The Associated Press.

The Reuters news agency said one of its reporters was killed in the initial strike as he operated a live television shot on an upper floor of Khan Younis’ Nasser Hospital. Other journalists, including Dagga, and rescue workers wearing orange emergency vests then raced up an external stairwell to reach the site, only to be hit by the second strike.

Video shot from below by pan-Arab channel Al Ghad showed their last moments as they climbed the stairs past damaged walls, followed by a boom and a huge plume of smoke from the strike.

Israeli Prime Minister Benjamin Netanyahu’s office called the strike a “tragic mishap” and said the military was investigating. He did not elaborate on the nature of the mistake.

Israeli media reported that troops fired two artillery shells, targeting what they suspected was a Hamas surveillance camera on the roof. Reporters from different outlets had regularly set up live TV shots at that location.

AP video shot by Oleg Cetinic