Dozens of football fans celebrating Liverpool’s Premier League victory have been mowed down by a car that ploughed into the dense crowd in “appalling scenes”.

Hundreds of thousands gathered to watch the team parade its trophy in the UK city of Liverpool on Tuesday morning (AEST) when the car accelerated into the throng.

Footage of the incident shows victims being knocked over like dominos and rebounding off the bonnet as others run to get out of the way.

The car then comes to a stop and the crowd swarms around it, banging and smashing the stationary vehicle.

A 53-year-old white British man has been arrested, with police saying investigation into the circumstances leading up to the incident is under way.

The incident is not being treated as terrorism.

Four people, including a child, had to be rescued from beneath the vehicle.

At least 27 people have been taken to hospital, although there were no reports so far of fatalities.

Another 20 victims were treated at the scene, with four children among the injured.

In an update early on Tuesday (Australian time), Merseyside police assistant Chief Constable Jenny Sims said the incident was believed to be isolated and not terror-related.

“I know that people will understandably be concerned by what has happened tonight,” she said.

“What I can tell you is that we believe this to be an isolated incident and we are not currently looking for anyone else in relation it. The incident is not being treated as terrorism.

“We would ask that people refrain from sharing distressing footage from the incident online and to please share any information directly with our investigation team.”

Sims said the motive for the incident was not yet known.

Emergency services wheel away a victim on a stretcher. Photo: AAP

Earlier, Merseyside Police said they were contacted just after 6pm (local time) following reports a car had collided with pedestrians on downtown Water Street.

“The car stopped at the scene and a male has been detained,” they said.

Police put up a huge cordon along on Water Street, in the heart of central Liverpool, while emergency vehicles lined the road.

A conscious man on a stretcher was seen being loaded into a St John’s ambulance. The paramedic told police he believed the Royal Hospital may be overwhelmed.

Police officers lined the junction of Castle Street and Water Street, while there were also firefighters on the scene.

Emergency vehicles, including ambulances, were allowed out of the cordon to leave the area.

Liverpool fans swarm the streets for the team’s victory parade. Photo: AAP

“The scenes in Liverpool are appalling — my thoughts are with all those injured or affected,” British Prime Minister Sir Keir Starmer wrote on X.

“I want to thank the police and emergency services for their swift and ongoing response to this shocking incident.

“I’m being kept updated on developments and ask that we give the police the space they need to investigate.”

Liverpool sealed the title last month with four games to spare and ended the season with a 10-point lead over second-placed Arsenal.

It lifted the trophy after a 1-1 draw with Crystal Palace at Anfield on Sunday.

During the celebrations earlier on Monday, the players and staff waved to the crowd from an open-top bus with the words “Ours. Again” emblazoned on the side, as red flares were lit along the route, running from Allerton Maze to Blundell Street.

-with AAP/PA