The first minister has promised a swift investigation and assured people “we have your back” after flooding forced them to flee their homes.

Rhun ap Iorwerth visited Gwaelod-y-Garth, on the outskirts of Cardiff, on Saturday after 15 properties were affected by flooding with 13 homes evacuated.

Roads have also closed due to debris and mud deposited by the flood water, according to Cardiff council.

The Breedon Group, owner of Taff’s Well quarry, said it would support the authorities and carry out its own investigation.

The Health and Safety Executive (HSE) said it would work with South Wales Police to investigate.

The first minister said he hoped the investigation would be “in-depth” and “give us the answers” to understand what had happened.

He said it was vital to make sure that lessons are learned and that it “can’t happen again”.

“This is a very different flooding experience to what we usually see.

“But the devastation in people’s homes is just as bad as in any serious flooding incident.”

He said there was “no obvious down-stream environmental impacts so far”, but stressed the need to wait for the investigation to be completed before speculating.

Residents on Heol Berry, where the flooding took place, were also told they will be offered assistance with temporary housing.

Residents said they heard a loud blast from the direction of Taff’s Well, Rhondda Cynon Taff, at about 12:30 BST on Thursday.

“Huge amounts of water” started rushing down the hillside with reports of water 5ft (1.5m) deep flooding some homes.

Main Road in Gwaelod-y-Garth and Heol Goch between Gwaelod-y-Garth and Pentyrch had to be closed for clean-up operations.

Highways and cleaning staff have been working on-site to clear the roads and remove debris, said Cardiff council.

However, significant damage has been caused to roads, it said, with mud, silt, debris and other obstructions.

Overnight accommodation was arranged for one family on Thursday, with support also provided to a second family on Friday, it added.