a criminal gang that relies on violence; a gang involved in large scale crimes UK, 1944.
2
the Metropolitan Police Flying Squad UK, 1999.
3
physically intimidating prison officers brought in to deal with rioting prisoners UK, 1996
heavy mob
A large group of people, especially one inclined toward violence or unrest. As the demonstration began, a heavy mob of masked men fell upon us and began assaulting anyone carrying a protest sign.
the ˈheavy mob/brigade
(British English, informal) a group of strong, often violent people employed to do something such as protect somebody: I had to laugh when he turned up at the meeting with his heavy mob, as if he was a mafia boss or something.