The riot broke out in Little India after a pedestrian was knocked down by a private bus and killed Sunday night.
Police said in a statement that the accident occurred at the junction of Race Course Road and Hampshire Road at about 9.25pm.
The statement said that a riot then broke out, involving about 400 people.
They damaged five police vehicles and several private vehicles.
Police later said in a press conference that 27 people, all of South Asian descent, had been arrested. Eighteen people, including 10 police officers and four Singapore Civil Defence Force (SCDF) officers, were taken to hospital with injuries.
The New Paper learnt that the driver of the private bus was dragged out and assaulted by a group of people.
His colleague, Madam Wong Gek Woon, 38, was cowering at the back of the bus as the angry mob smashed the windows and tried to hoist themselves into the vehicle to get to its occupants.
Her husband, Mr Alan Wee, 50, told TNP at Tan Tock Seng Hospital (TTSH) early this morning that she coordinates the buses for the company and was in Little India when someone told her one of its buses had been involved in an accident.
The bus was filled with workers being taken back to their dormitory.
Mr Wee said she went to check and someone told her to get into the bus as it was getting dangerous.