A man has been praised for stepping forward to tackle the flames engulfing a London bus armed with nothing but a fire extinguisher from his workplace.Passers-by filmed the bus as it burned, billowing thick black smoke after the fire broke out on a main road in West Hampstead.There was a “loud bang”, according to witnesses, as the vehicle burst into flames. He took on the blaze The bus was the 113 service on Finchley Road, outside Finchley and Frognal station, and set on fire last night.A security worker from a nearby office rushed out, armed with a fire extinguisher from his workplace, to tackle the flames.He was praised by witnesses as he ran towards the burning bus, dressed in a suit and tie.A witness said: “He wasn’t wearing a mask or anything like that, he just ran out and did what he could. He is a hero. At one point he was so close to the flames, people were shouting at him to get back.”A Transport for London spokeswoman said: “There were no injuries sustained by the passengers or driver and investigations as to the cause of the incident are under way”. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings.