Gangs of bikers and youths pelting fireworks caused Halloween chaos for emergency services across the UK.
More than 200 motorcyclists gathered for a "Halloween ride out" in Solihull and Birmingham, while in Leeds a group of more than 50 people racing off-road motorcycles and quad bikes brought Kirkstall Road to a standstill.
Fireworks were thrown at police in two separate attacks caught on video, with one officer narrowly avoiding being hit by an explosive in Tottenham, north London, the Metropolitan police said. A youth was detained over the attack.
Footage from the dashcam of a car being driven by neighbourhood watch group Shomrim showed a firework fly past a Met officer. The rocket then ricocheted and exploded next to a police car.
Officers in Birmingham also tweeted footage of one of their vans being hit by a volley of fireworks.
There were similar scenes in Coalisland as youths with fireworks attacked fire crews, with hostile crowds forcing them to withdraw from incidents in Rostrevor and Newry, Northern Ireland fire and rescue service said.
At least seven people were arrested and 10 motorcycles seized following the incident in Birmingham, West Midlands police said.
The riders, many of whom were wearing face masks, darted between traffic, jumped red lights and performed stunts on busy main roads.
The fire service also reported that a group of bikers were stopping them from responding to an emergency call.
Ch Insp Jack Hadley of West Midlands police described it as "outrageous" and "totally unacceptable".
"This wasn't a rally of bike enthusiasts – this was loutish, criminal behaviour," he said. "Bikers were riding without lights, at speed, dangerously, pulling wheelies in the street, mounting pavements and damaging vehicles."
In Leeds, Kirkstall Road was closed for 90 minutes as police waited for the bikers to disperse.
Witnesses described the scene as "utter chaos" and "madness" and compared it to the film Mad Max. It is thought the event was organised on social media. No arrests were made, West Yorkshire police said.