Hamas terrorists attacked a group of humanitarian workers in Gaza Wednesday night, killing at least five and wounding several others.

The U.S.-backed Gaza Humanitarian Foundation shared an urgent update about the attack and said the incident took place after days of Hamas threats towards its employees. The foundation believes some of its employees might have been taken hostage by Hamas, potentially adding to the total of innocent people the terror group is holding in captivity.

“We are still gathering facts, but what we know is devastating: there are at least five fatalities, multiple injuries, and fear that some of our team members may have been taken hostage. We condemn this heinous and deliberate attack in the strongest possible terms,” the foundation said in a statement.

“These were aid workers. Humanitarians. Fathers, brothers, sons, and friends, who were risking their lives everyday to help others. Our hearts are broken and our thoughts and prayers are with every victim, every family, and every person still unaccounted for.”

The team was en route to a distribution center and working alongside local Palestinians to deliver aid to the Gazan population. They were attacked around 10 p.m., Gaza time, as they were on a bus.

The Gaza Humanitarian Foundation called on the international observers to condemn the attack and placed sole responsibility for it on Hamas. In the days leading up to Hamas’s attack, the foundation faced threats from Hamas, but they were met with silence. It will disclose more information when it becomes available.

Hamas’s attack could complicate humanitarian efforts to aid the Gazan population moving forward as Israel’s war against the terrorist group continues. Critics of Israel frequently blame the Jewish state for minimizing the amount of humanitarian aid flowing into Gaza during the war, which has lasted over 500 days. The war began due to Hamas’s mass slaughter of Israeli civilians on October 7, 2023, and its abduction of over 250 hostages.