The fire started at around 10.30 pm and spread so quickly that part-time firefighters, off-duty personnel and some on holiday were all called in to help.
Firefighters were still at the scene today in case it flared up again.
Speaking from the scene this morning, station manager Clive Russell said that the fire had been a serious one, but not the biggest Jersey had ever seen.
It was almost certainly caused by a firework display booked by a wedding party at the Water’s Edge Hotel.
‘We can say without significant doubt that it was caused by a misfired firework as part of an organised display that went off in the undergrowth instead of out to sea,’ he said.
‘Because it was an exploding-type firework it blew up in the gorse and heathland.’