People have died following a major river rescue operation, the BBC has been told.
It has been confirmed that one person was taken to hospital after being pulled from the River Cleddau.
Town councillor Thomas Tudor called it a “terrible tragedy” and sent his sympathies “to the families who have lost loved ones”.
Police launched a search after reports that a group of people were in distress in Haverfordwest, Pembrokeshire.
Dyfed-Powys Police, firefighters, coastguard, ambulance crews and four helicopters were deployed to the stretch of the river at Quay Street about 09: 00 BST.
A police spokeswoman said: “A swift search of the river was launched, with 30 firefighters from Mid and West Wales Fire and Rescue Service working alongside Coastguard crews and helicopter support.”
Det Ch Insp Jonathan Rees of Dyfed-Powys Police said he was not in a position to release further details at this time, but everyone had been accounted for and the search stood down.
He said at present his priority was ensuring those involved, and their families, had been contacted and were receiving appropriate support.
An investigation is under way into the circumstances.
Mr Tudor said: “Today a terrible tragedy unfolded on the River Cleddau in the Castle Ward of Haverfordwest.
“I would like to extend my sympathies to the families who have lost loved ones in this tragedy and I would like to thank the emergency services for their brave efforts in tackling this issue.
“I would also like to thank the staff from the Bristol Trader and Vaughans Radio who provided help and support for the emergency services during this difficult operation.”
The Welsh Ambulance Service confirmed one patient was taken to the town’s Withybush Hospital for treatment.
Earlier Dyfed-Powys Police asked people to avoid the area around Quay Street.
There is a flood alert on rivers in the western Cleddau catchment area following heavy rain on Friday.
The Met Office has issued a warning for more heavy rain across south Wales on Sunday.
It comes after a landslide closed a road in Gwynedd following torrential rain.
The Severn rail tunnel between Wales and England was forced to close on Friday evening due to flooding.
In a statement, the RNLI said a crew was launched from nearby Angle to help with the search on Saturday morning, but has since been stood down.
At the scene: BBC Wales reporter Garry Owen
People in this tight-knit community are obviously upset and shocked at what happened here today.
It’s said the conditions in the river were dangerous at about 9 o’clock this morning.
There had been a heavy and sudden downpour of rain which came amid warnings to be careful.
There were dangerous and fast-flowing flood waters following heavy rain in the last few days.
This has been an intensive operation with the emergency services called to the scene.
They were brought in from a wide area to help in the effort.
Yellow weather warnings for rain also remain in several parts of the country, including Glasgow, where the global COP26 climate summit is due to begin on Sunday.
On Saturday afternoon, seven flood warnings remained in place, meaning that flooding is expected, and 46 flood alerts, meaning that flooding remains likely.
In Dartmoor, Devon, parts of the area received 125mm (4.9in) of rain in 48 hours – compared with an October average of 130mm (5.1in).
It comes after a week of wet weather which saw disruption and destruction in northern areas including Cumbria and southern Scotland.