Large-scale disorder broke out in Swansea as a vigil descended into violence.
Police warned people to stay indoors amid chaotic scenes on the streets of the city’s Mayhill area on Thursday night.
Images and footage posted on social media showed cars on fire in the middle of the road and crowds cheering as a vehicle was rolled down a hill.
Local Welsh Parliament member Tom Giffard called the scenes “disturbing”, while Welsh secretary and Carmarthen West and South Pembrokeshire MP Simon Hart said: “A tough night for the police dealing with such reckless behaviour. No excuses, police right to robustly respond.”
South Wales Police Superintendent Tim Morgan said that what was believed to have started as a vigil for a recently-deceased local resident had escalated into “violence, criminal damage and a wanton disregard for public safety”.
He added: “We have a number of officers at the scene working to de-escalate the situation as quickly as possible and allow other emergency service colleagues to attend to calls in the area.
“The incident is still on-going and we urge anyone involved to leave the scene immediately.
“Those involved can expect to face robust action. Post-incident investigations will also aim to identify all those concerned.
“In the meantime, we urge local residents to stay indoors while the matter is brought to a safe conclusion.”