A passenger bus swerved off course and drove into a busy pedestrian underpass, in Moscow, Russia December 25, 2017. REUTERS

A bus in Moscow plowed into a subway station Monday killing at least four and injuring at least 15 people, according to Moscow Times.

Security footage shows a bus start moving from a standstill at a highway bus stop onto a sidewalk and down a set of stairs into the entrance of the Slaviansky Boulevard metro station.

There is currently no sign of terrorism in the incident. The bus driver operating the vehicle told investigators that the bus started moving suddenly and that he applied the brakes, but they did not work. The incident happened in icy conditions, according to the BBC. The driver was taken into police custody and local reports have said that he was sober.

The people killed in the accident were crushed by the bus as it moved toward the station. The bus was only one year old and Moscow mayor Sergei Sobyanin said that all buses will be inspected after the accident, according to the Interfax news agency.

Monday was a normal work day in Russia where Orthodox Christmas is celebrated Jan. 7.

A deadly train accident happened near the same station in 2014, 21 people were killed when a train derailed between two stations. The train was between Slaviansky Boulevard and Victory Park stations when it stopped suddenly. At least 50 other people were seriously hurt in the crash and more than 1,100 people had to be evacuated.