Multiple aid workers were killed after a bus was attacked in Gaza on Wednesday night, according to a US-backed humanitarian aid organization which accused Hamas of carrying out the assault.

“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,” GHF said in a statement.

The group was en route to a distribution center in the area west of Khan Younis, GHF said, adding further details would be provided once they became known.