Police in Singapore arrested 27 people after clashes between rioters and officers near the city centre late on Sunday.
The trouble began after a migrant worker was knocked down and killed by a bus in a district known as Little India.
About 400 foreign workers took to the streets, hurling railings at police and torching police cars and an ambulance.
At least 18 people were hurt, most of them police officers, before the trouble was brought under control.
Police commissioner Ng Joo Hee said it was the first rioting in Singapore in more than 30 years.
"It is not the Singapore way," he said.
The BBC reports any outbreak of public disorder is rare in Singapore, which depends heavily on foreign workers, with migrant labourers from South Asia dominating sectors like construction.
Many congregate in Little India on Sundays to shop, drink and socialise.
Rioting in Singapore is punishable by up to seven years in prison plus caning.
