World Central Kitchen says the killed aid workers including Britons John Chapman, James Henderson and James Kirby were travelling in three cars - two of them armoured before the Israeli air strike.
The convoy pulled out of the organisation’s warehouse south of Gaza City on Monday night to distribute aid to Palestinians.
Their movements had been co-ordinated with the Israel Defense Forces, followed an IDF-approved route, and had GPS trackers and SOS beacons broadcasting their positions, the charity said.
But despite taking precautions, a member of the IDF unit identified an armed man as a potential threat on one of the trucks that had accompanied the three humanitarian vehicles, a security source told Israeli newspaper Haaretz.
Forces had reportedly seen the volunteers entering the main distribution hub in Deir al-Balah with a larger convoy to collect the aid.
While neither the suspect nor the truck left with the WCK cars, a Hermes 450 drone, or unmanned aerial vehicle, was scrambled to follow them.
Two of the cars had some form of armour plating, while the third was a “soft-skin” 4x4. All had clear WCK markings on the roof and doors.
However, the IDF unit ordered drone operators to attack one of the vehicles shortly before midnight.
It deployed a precision R9X Hellfire missile which smashed into one of the armoured cars. Passengers were seen scrambling from the wreckage and jumping into the other two vehicles.
They informed authorities monitoring their movements that they had been hit and sped off. After travelling just 900 metres, the Hermes 450 fired once more.
The second armoured car was hit, leaving just the soft-skinned 4x4 remaining. Surviving passengers loaded the wounded into the final vehicle and pulled away.
But having made it 1.5km further along the coastal road the drone fired for a third time - blasting the remaining vehicle to bits.
