The footage, shot in the London borough of Islington, shows the workers watching from the RSPCA Harmsworth Memorial Animal Hospital in Holloway. Just outside, fireworks can be seen streaming down the street at a police car parked just yards away.
One of the workers can be heard saying: “Just think of all the animals, you utter b**s!”
Another, watching the fireworks explode against nearby buildings, says: “It’s like a warzone.”
At one point, the explosions subside before a further flurry are launched, forcing the police vehicle to back away.
One of the fireworks explodes just feet away from the RSPCA workers, who were luckily watching from indoors.
The footage, posted by Twitter user 999London, prompted furious replies from social media users, who said: “Ban the sale of fireworks to the general public. It’s beyond a joke every year.”
Another said the incident, which appeared to target the police car, was “dreadful and disgusting”.
The user posting the footage referred to the attackers as “yobs”.