Three people have been stabbed and three others have been injured following reports of a "large disturbance" in Cardiff.
A huge police presence was seen in the Welsh city on Saturday night, with people sharing photos and footage from the scene on social media.
Queen Street, one of the main roads in the city centre, was cordoned off as officers while officers remained at the scene.
One of them suffered head injuries and remains in a serious condition, police said.
Three others are believed to have sustained stab wounds, South Wales Police added.
Two more people attended hospital with lesser injuries, according to the police force.
The police force said in a statement: "We are investigating a large disturbance which occurred in Cardiff city centre on Saturday night.
"Multiple reports of a violent incident on Queen Street were received at around 9.50pm.
"Six people have subsequently been taken to, or self-presented at, the University Hospital of Wales with various injuries.
"One person suffered head injuries and remains in a serious condition, while three others are believed to have sustained stab wounds.
"Two others have presented at hospital with lesser injuries."
One eyewitness shared a video on Twitter showing a number of police cars and ambulances.
Another passer-by said there were about "50 emergency service vehicles" on the street, Wales Online reports.
Eyewitness Sophie Zermatten, 27, said: “I heard a lot of police sirens so went to see what the noise was.
"There was a large area by the Capitol Shopping Centre cordoned off and another area nearby. “
She added: “There were lots of police cars and officers.
"It looked like the incident was over by the time I had got there, but it was clear that something big or serious had happened by the sheer number of police involved."
A 20-year-old from Fairwater was at the Ernest Willows pub in City Road when police arrived.
The man, who only wanted to be known by his first name Ryan, said: “I was with my friends (in the pub) and we were suddenly told to leave.
"We heard a bartender/server say they heard (something like) fireworks and we all had to leave immediately.
"I didn't hear anything myself, but once I left the pub onto the road it was was blocked off at the end by Newport Road.
“Outside the pub was covered in police cars vans and officers standing on the road. I asked an officer what had happened - but was told that they could not tell me.”
Masters student Elizabeth Winter, 25, was having a walk in the city centre when she saw a large police presence at the top of city road.
She said: “There was a group of young men shouting at police. There were around four or five officers shouting back.
"I overheard someone saying that someone had been ‘cheffed’ - street slang for a stabbing.”
Another picture from Cardiff city centre shows an area of Windsor Place cordoned off by police.
Mirror Online has contacted South Wales Police for comment.
