The only survivor is a baby girl who was reportedly handed or thrown out of a car window before the “tragedy” in County Donegal.
Five members of the same family have died after a car entered the water at Buncrana pier, County Donegal.
At least two children are understood to have been in the vehicle at the time the “tragic accident” occurred.
Emergency services said they have recovered the bodies of two boys, a man and a woman, and a second female, whose age has not been confirmed.
It is not clear how the car, which is believed to have a Northern Ireland registration plate, ended up in Lough Swilly.
It is thought the slipway leading down to the lough was covered in algae and may have been slippery.
A baby girl was rescued from the car with the assistance of a bystander, Gardai confirmed.
Unconfirmed reports suggest she was handed or thrown out of a window just seconds before the car went into the water.
The child is said to be in a stable condition in hospital.
Sky’s Ireland Correspondent David Blevins said: “At this stage, Malin Head coastguard is confirming that there are five fatalities.
“There are adults and children among the dead.
“An infant has been recovered from the water and taken to hospital in Letterkenny, County Donegal.
“A major search and rescue operation is ongoing and has been going on for a couple of hours now.
“Fishing crews that have come back are assisting with the lifeboat crews and the coastguard helicopter.
“We understand that a jeep with a family on board entered the water at the pier from Buncrana in what’s being described now as a tragic accident.
“This will be an area that is very popular with families from all over Ireland – from Donegal and indeed from Northern Ireland, which is not far over the Irish border.”
It is believed the family may have stopped to admire the sunset.
An Irish police spokesman said: “Gardai and emergency services are at the scene of an incident that occurred at Buncrana Pier.
“A car entered the water and a search of the area is currently ongoing. No further information at present.”
The coastguard said the accident happened at around 7.45pm on Sunday.
Northern Ireland Deputy First Minister Martin McGuinness said on Twitter: “Very sad news of fatalities in an incident at Buncrana Pier.
“Thoughts are with relatives of those involved and rescue services.”
:: Gardaí are appealing for witnesses and anyone with information is asked to contact Buncrana Garda Station on 074 9320540, The Garda Confidential Line, 1800 666111 or any Garda Station.