Four people have died after the car in which they were travelling plunged into a reservoir in mid-Wales - with reports they were all from the same family.
Emergency services attend the scene of the fatal crash
One survivor, a woman who has not been named, was pulled out of the wreckage of the smash near Llanidloes, Powys.
She was at the wheel of a Peugeot 807. Police said the body of one man had been recovered from the car, which remains submerged in water.
The other three bodies are still in the vehicle.
Police have declined to comment on reports that those remaining in the car were all children, but it is understood they had travelled to the area from Pontypridd for a holiday.
A man has been arrested on suspicion of causing death by dangerous driving and is being held by police.
The second car involved in the accident, which happened at the Bwlch y Gle Dam on the B4518 road, was a Ford Mondeo.
A police spokesman said: "We can also confirm that the woman holidaymaker driving the Peugeot managed to escape from the car and is now receiving medical attention - but tragically four other occupants of that car have been killed.
"The body of a man has been recovered from the car - but the other bodies remain submerged and arrangements are being made to recover them."
He said the road had been closed and would remain so for some time.
He added: "We are in the process of informing next of kin, and no further information in relation to the victims will be released until this process has been completed."
Steve Dimmick, one of the first to arrive at the scene of the crash, told Sky News about the pandemonium at the scene.
He said: "We're really shook up. We've heard the rumours that it could be a family. It's just horrifying."
A woman who works nearby said she had heard one vehicle had clipped another one, sending one of them into the water.
"We saw lots of police cars going past, ambulances and two recovery boats," said the woman, who did not want to be named.
RAF Valley, based in Anglesey, sent a Sea King helicopter search and rescue crew.
Mid and West Wales Fire and Rescue Service said two fire crews and two boats were involved in the operation.
The area where the crash happened is regarded as a rural beauty spot, largely made up of farming communities.
Emergency services attend the scene of the fatal crash
One survivor, a woman who has not been named, was pulled out of the wreckage of the smash near Llanidloes, Powys.
She was at the wheel of a Peugeot 807. Police said the body of one man had been recovered from the car, which remains submerged in water.
The other three bodies are still in the vehicle.
Police have declined to comment on reports that those remaining in the car were all children, but it is understood they had travelled to the area from Pontypridd for a holiday.
A man has been arrested on suspicion of causing death by dangerous driving and is being held by police.
The second car involved in the accident, which happened at the Bwlch y Gle Dam on the B4518 road, was a Ford Mondeo.
A police spokesman said: "We can also confirm that the woman holidaymaker driving the Peugeot managed to escape from the car and is now receiving medical attention - but tragically four other occupants of that car have been killed.
"The body of a man has been recovered from the car - but the other bodies remain submerged and arrangements are being made to recover them."
He said the road had been closed and would remain so for some time.
He added: "We are in the process of informing next of kin, and no further information in relation to the victims will be released until this process has been completed."
Steve Dimmick, one of the first to arrive at the scene of the crash, told Sky News about the pandemonium at the scene.
He said: "We're really shook up. We've heard the rumours that it could be a family. It's just horrifying."
A woman who works nearby said she had heard one vehicle had clipped another one, sending one of them into the water.
"We saw lots of police cars going past, ambulances and two recovery boats," said the woman, who did not want to be named.
RAF Valley, based in Anglesey, sent a Sea King helicopter search and rescue crew.
Mid and West Wales Fire and Rescue Service said two fire crews and two boats were involved in the operation.
The area where the crash happened is regarded as a rural beauty spot, largely made up of farming communities.