Two police officers were injured in a "shocking and despicable" Bonfire Night attack when bricks were thrown through the window of their van.
The attack in Preston, Lancashire, left the officers with cuts caused by broken glass.
Three men, aged 18, 19 and 20, were arrested and several "incendiary-type" fireworks were found, police said.
Elsewhere in Lancashire, a gang of children hurled fireworks at officers in Blackburn.
Police who responded to the Preston incident in Grizedale Crescent, also had fireworks thrown at them.
Supt Karen Edwards described the incident as "shocking and despicable" and "cowardly" adding that it was "only luck" that prevented more serious injuries.
"I find it staggering in this day and age that our officers continue to be targeted and attacked," she continued.