A rescue helicopter has crashed near the world’s longest zip line, killing its entire crew, in Ras al-Khaimah in the north-east of the United Arab Emirates.

The state-run WAM news agency says the crash took place during a rescue mission at around 5.50pm local time on Saturday. Officials did not immediately release a death toll.

Videos posted online show the helicopter diving into a tailspin before crashing and bursting into flames in the valley of a rocky mountain.

Ras al-Khaimah’s ruler, Sheikh Saud bin Saqr al-Qasimi, ordered an immediate investigation into the crash. The zip line, the world’s longest at 2.83km, is located at the UAE’s highest mountain in Jebel Jais and opened in February.