Former councillor Jacqui Gasson says "the whole area of Ely fire station is closed off.
"The whole of the front of Ely fire station is closed off with blue crime scene tape. There are police numbers used to mark evidence all over the yard of the fire station. I counted twenty odd of the yellow markings with numbers of them," says former councillor Jacqui Gasson
Leckwith Retail Park - which is next to the Cardiff City Stadium, home of Cardiff City FC - has been closed, according to eyewitnesses, and ambulances are at the scene.
Lynda Paterson, who lives on Cowbridge Road West, told the BBC that the scene outside her house was chaos.
"I was going to pick my children up from school and I could see there were police and someone was lying on the floor, on the pavement," she told the BBC
"I could see police running back and forth along the road and I now know there was a child... who had been hit.
"The police were running down because the ambulance hadn't come."
Wales star Jamie Roberts tweets: "So some clown has driven around Ely & Leckwith doing hit & runs putting 11 people in hospital...what is wrong with people??"
It is confirmed that the emergency department at the University Hospital of Wales, Cardiff, is closed to all emergency admissions aside from those involved in the incident
Any emergency admissions are being diverted to the Aneurin Bevan health board in Gwent until further notice.
Eyewitnesses described people crying and hugging in the streets in Ely.
Witnesses at Asda in Leckwith say two women were hit at the petrol station, by the forecourt, around 3.45pm today
Eyewitnesses reporting a woman in her twenties was knocked down along with her three children in the forecourt of the fire station on Cowbridge Road West in Ely. It is believed that she has died, and the children were injured.
Our reporter Peter Law in Ely reports eyewitnesses in Ely said the van went from the fire station on Cowbridge Road West to Grand Avenue. There it knocked down a woman and a younger girl at a zebra crossing.
Both the woman and the girl hit at the zebra crossing are believed to have been injured. An eyewitness said: "The girl had injured her ankle and blood on her face".
The older woman hit at a zebra crossing was given a mask by paramedics and was reported to be screaming by eyewitnesses
Hailie Jacobs, from Ely, told the BBC that the incident had left her scared.
"I noticed all the police and ambulance first. They'd taped off the road in various parts," she said.
"Some of it was absolutely manic and there was a paramedic working on someone on the ground.
"There were just loads of ambulances and police cars and even two helicopters above.
"It was all quite scary, we live near there and it's all places where I walk my children."
One eyewitness, Stuart Bateman, who was sat on a bus outside the fire station on Western Avenue says he saw a white van on the side of the road and a woman was waving frantically at it as he got off the bus.
He said: "There was complete panic. the van sped off away from the fire station and a silver car chased it.
"I dialled 999 and somebody else got the registration number of the van.
"There was a quick response ambulance at the fire station and the paramedic tended to a woman who was most badly injured.
"Then a police car arrived to help. I could see there were people on the ground but I am not sure whether one of them was a child.
"There was still complete panic."
"It's scary, I've never been round anything like this before, " passers-by tell the BBC
The owner of Cardiff Reptile Centre told WalesOnline reporter Peter Law that he saw a couple with a baby in a pram being hit outside his shop. The baby was thrown four or five feet from the pram.
The owner described the van swerving across four lanes of Cowbridge Road West before hitting the couple and the pram. He said the baby's face was covered in blood and the injuries were so bad he couldn't see where the blood was coming from.
The baby's father was ok and was tending to the baby, while the reptile shop owner tended to the mum. The mum's leg was twisted and she was screaming out to her child.
Police press conference to be held at 7pm. Live updates will follow here.
Businesswoman Dr Elizabeth Haywood, who is also the wife of Peter Hain, was at Asda in Leckwith between 3.30pm and 4pm and witnessed the incidents
Ms Haywood said: "I was filling up with petrol and I saw a taxi driver going to help another guy who had been hit on the head with a steering wheel immobiliser. I think he got hit as well.
“The guy who was hitting them walked over to his white van which was parked at the petrol pumps.
“I checked his registration number and meanwhile the taxi driver ahead of me at the pump got back into his car shaken up and drove off.
“Just as I was making the phonecall to the emergency services the white van that had been sitting there for a while suddenly sped off, screeching and with smoke coming from the tyres.
She added: "The next thing I heard was a scream and a thump.
“There was a woman who was in front of his van who was hitting the front of his bonnet because he had hit her. She then went under the wheels of his van.
“So we were all screaming ‘back-up, back-up’. There were a lot of people there.
“So he did back up and then he ran over her again.
Describing the scene at Asda in Leckwith, Ms Heywood said: "Then this other woman came up to the van to get him to stop and he ran over her as well and he dragged them both to the corner of the roundabout and out into the road which leads back onto the main road and he hit another man coming the other way who opened his car door to stop him.
“He just drove into his car door and sped off with screeching tyres down the road leaving the two women very seriously injured."
The police press conference is due to start imminently at Cardiff Bay police station
Press conference may be delayed, reporters at Cardiff Bay police station say. It is expected to be in the next 20 minutes.
The Welsh Ambulance Service says the total number of casualties in the Cardiff hit and run incidents is now 12. Full press release follows.
A Welsh Ambulance Service spokesperson said: “The Welsh Ambulance Service has responded to a number of road traffic collisions in the Ely and Leckwith areas of Cardiff this afternoon.
“Eight emergency ambulances, five rapid response vehicles, four ambulance officers, two basics doctors and one Helimed attended several calls along Crossways Road, Cowbridge Road West, Grand Avenue, and Sloper Road.
“Twelve casualties, including adults and children, have been taken to the University Hospital of Wales with various injuries, some serious.
The A&E Dept at UHW has been closed to anything other than casualties related to these incidents. In the meantime, the ambulance service is liaising with hospitals in the region including The Royal Gwent and The Royal Glamorgan to convey emergency patients.”
Police press conference due to start immediately, reporters heading into the briefing room with officers now.
Reverend Jan Gould, of the Church of the Resurrection, said the Ely community had been left "deeply shocked" by today's events.
"We have opened the church if anybody wants to come in," she said. "It's a deeply shocking incident and nothing I have ever remembered in my ministry is as traumatic as this."
Aaron Ward, who lives off Cowbridge Road West, was at the retail park at Leckwith moments after the drama unfolded.
He said: "I pitched in and helped however I could. I just saw the back of the white van and police rushing in. He hit two women and dragged them 250 yards under the van.
"The mother was in a serious condition. The daughter was complaining of spinal injuries. I just dragged the first aid kit from one of the police vans and pitched in however I could, applying pressure to injuries and helping paramedics.
"The injuries were horrific, where she [the mother] had been dragged along the road. It's absolutely disgusting what's happened."
We're still waiting for the press conference to begin. Updates here.