A white substance was dropped by two drones hovering above the Madleen before communication with the ship was cut off, says the cofounder of the International Solidarity Movement Huwaida Arraf while speaking to Al Jazeera.

“We know that they had two drones hovering above them that dropped some kind of chemical on the vessel. We don’t know what that chemical was,” she said.

“Some people reported that their eyes were burning. Before that, they were also approached by vessels in a very threatening manner.”