At least four people have been killed and 20 are in hospital in Finland after a bus drove off the side of a bridge and crashed into railway tracks below. Emergency crews rushed to the scene in the Finnish city of Kuopio after the accident, which has been attributed to brake failure. Four people died while 20 people injured in the crash were transported to Kuopio University Hospital. Three are severely injured, 6 are injured, and 11 are mildly injured. Kuopio University Hospital has tweeted: "Three people perished at the site and one in transit."If necessary, the parties will be provided with the possibility of overnight accommodation." Finnish Prime Minister Juha Sipila tweeted "sad news from Kuopio," and expressed his condolences to the victims. The bus had smashed into five cars stopped at a red light on the bridge before driving off the edge and falling onto the railway. Police spokesman Miika Mutanen told The Associated Press: "We spoke briefly to the bus driver who told us he wanted to brake but they didn't work and that he tried to avoid other vehicles." There was no train on the tracks at the time of the accident at around 3 pm. The bus belonged to the Kemin Liikenne company. Finnish police have tweeted: "The police, together with the city of Kuopio, are organising crisis aid due to a serious road accident." Railway operator VR said that all train traffic on the stretch had been halted and passengers were being transported by bus instead.