Six police officers have been injured after they were targeted on Bonfire Night by groups of people throwing fireworks and setting bins alight.
Dozens of officers in riot gear were deployed in the Harehills area of Leeds when the chaos broke out at 20:20 GMT.
Fifteen "local males", aged between 11 and 23, have been arrested on suspicion of violent disorder, West Yorkshire Police said.
The force said offenders were "naive to think there will not be consequences".
Two of the injured officers were treated in hospital but were not seriously hurt. The others suffered minor injuries.
A helicopter was deployed as the mayhem unfolded on Tuesday.
Officers came under attack as they were dealing with a wheelie bin that had been set on fire. Passing motorists were also targeted.
Other bins were then moved into the road and set alight as the number of young people involved increased, West Yorkshire Police said.
Officers used "public order tactics" to disperse the groups and make arrests, the force added.
In Greater Manchester, firefighters responding to an out-of-control bonfire in Hyde were attacked by a gang of 40 young people throwing fireworks.
Crews were also targeted in Oldham.
One Leeds resident, who did not want to be named, said bricks were thrown at shop windows and police cars.
"They were all coming up the road, they had rockets in their hands and police were backing off," he said.
He added his door was open and young children "were coming in here to get away from it".
Police said a "full post-incident investigation" had begun and detectives were checking CCTV footage and scanning helicopter pictures and images captured from body-worn cameras.
Ch Supt Steve Cotter said the behaviour was "completely unacceptable" but added there was "no suggestion this was a result of tension in the community or animosity towards the police".
He added: "This appears to have been about a hooligan element of local youths seeing an opportunity on Bonfire Night to engage in firework-related disorder on a large scale.
"They are naive if they think their actions won't have consequences and we will be sending a very clear message to them over the coming days and weeks".