Singapore's civil defence officers extinguish burning vehicles following a riot in Singapore's Little India district late December 8, 2013. Local media said a mob of about 400 set fire to an ambulance and police cars during the riot on Sunday, which started after a bus knocked down a pedestrian. REUTERS/Dennis Thong/Lianhe Zaobao (SINGAPORE - Tags: CIVIL UNREST) ATTENTION EDITORS - THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. IT IS DISTRIBUTED, EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS. NO SALES. NO ARCHIVES. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. SINGAPORE OUT. NO COMMERCIAL OR EDITORIAL SALES IN SINGAPORE

Hundreds of South Asian workers rioted in Singapore late Sunday after being enraged by a fatal road accident, leaving 18 people injured and police vehicles burnt in the city-state's worst outbreak of violence in more than 40 years.

A police statement said the disturbance started in the congested Little India district when a 33-year-old Indian man was killed after being hit by a private bus.

Police said about 400 people on the scene began rioting, attacking the bus as well as police vehicles after officers responded to reports of a commotion.

Ten policemen, four civil defence staff and the bus driver and conductor were among the injured, but none were seriously hurt, officials said.

A total of 27 South Asian workers were arrested on charges of rioting, which is punishable by up to seven years in prison plus caning, police said.

Prime Minister Lee Hsien Loong said in a statement that "whatever events may have sparked the rioting, there is no excuse for such violent, destructive, and criminal behaviour."

"We will spare no effort to identify the culprits and deal with them with the full force of the law," he added.

Five vehicles including three police cars and a civil defence ambulance were burnt while pictures and videos posted in social media showed two police cars being overturned by a cheering mob. Several private vehicles were also damaged in the fracas.

The situation was brought under control after the elite Special Operations Command and Gurkhas working for the police arrived on the scene.

The rare outbreak of public disorder in strictly governed Singapore took place in an area normally packed with thousands of workers, mostly from the Indian subcontinent, on their day off.

"Let me say that the incident that happened last night is intolerable. Rioting, destruction of property, it is not the Singapore way," Commissioner of Police Ng Joo Hee said at a news conference in the early hours of Monday morning.

State-linked broadcaster MediaCorp said it was the first riot in Singapore since racial disturbances in 1969.

Singapore depends heavily on guest workers, with labourers from South Asia dominating sectors like construction. Many congregate in Little India on Sundays to shop, dine and drink.

The incident immediately triggered online attacks on foreign workers in Singapore, but officials called for calm and warned against speculation.

Anyone who is found to be armed in a riot or using objects as weapons that can cause death can be jailed up to 10 years with the possibility of caning, a punishment reserved for serious crimes.