(CNN) -- A hot air balloon crash in New Zealand early Saturday killed 11 people -- the pilot and 10 passengers -- officials said.
No one survived the crash, which happened on the outskirts of Carterton, a town northeast of Wellington.
A fire likely started on board the balloon, sending it plummeting to the ground, said Superintendent Mike Rusbatch, Wellington District commander for New Zealand Police.
It was not immediately clear what started the fire, though eyewitnesses said the balloon had hit a power line, according to police.
"This is an absolutely tragic incident and our thoughts are with the families of the deceased. We are in the process of notifying next of kin. However, we will not be releasing any names until all next of kin have been advised," Rusbatch said.
A police spokeswoman said all the victims were from the wider Wellington area.
An investigation into the cause of the accident is under way.
A witness to the crash told Radio New Zealand that the balloon was on fire as it fell. He was in his garden when he heard a hissing sound and looked up to see flames climbing the sides of the basket. When the balloon hit the ground, a large cloud of smoke ascended, Radio New Zealand reported.
The weather was likely not a factor in the crash, according to Jill Stringer, a spokeswoman for the Wairarapa District Health Board.
"It was a perfect morning for ballooning," she said.
CNN's Samira Said contributed to this report.