The bodies of 15 aid workers - eight medics working for the Palestine Red Crescent Society (PRCS), six civil defence members, and one United Nations employee - were found in a "mass grave" after the incident, according to the head of the UN Office for Coordination of Humanitarian Affairs Jonathan Whittall, SKY News reported.
The Israeli military said it is investigating - claiming before the video came to light that its initial inquiry found its troops opened fire on vehicles without headlights or emergency signals, which therefore looked "suspicious". It also says there was an evacuation order in place in the area at the time of the incident.
But video footage obtained by the PRCS - and verified by Sky News - shows ambulances and a fire vehicle clearly marked with flashing red lights.
Sky News has used aftermath video and satellite imagery to verify the location and timing of the footage.
It was filmed on 23 March north of Rafah. It shows a convoy of marked ambulances and a fire-fighting vehicle travelling south along a road towards central Rafah. All of the vehicles visible in the convoy have their flashing lights on.
It was filmed early in the morning, with a satellite image seen by Sky News taken at 9.48am local time on the same day showing a group of vehicles bunched together off the road.
The PRCS first posted about losing contact with its crews just before 7am local time.
Satellite imagery shows the area on 26 March, three days later. Tyre tracks are visible, as are groundworks likely created by military vehicles.
The footage is first filmed from inside a moving vehicle, through the windscreen a convoy of vehicles is visible - including ambulances and a fire truck with flashing emergency signal lights.
When the convoy stops, a vehicle is seen having veered off the road to the left-hand side.
The vehicle where the video is being filmed from stops and the aid workers get out. Intense gunfire then breaks out and continues for around five minutes.
The paramedic filming the video is heard saying in Arabic that there are Israelis present - and reciting a declaration of faith used before someone dies.
Hebrew voices are also heard in the background but it is not clear what they are saying, the Sky report added.
MNA
Your Comment