At least 5,000 more workers protested in Dhaka's up-market Gulshan area where many embassies and foreign aid groups have their offices.
On Tuesday, the government said it would raise the minimum wage for garment workers from 1,662 taka - the lowest industry salary worldwide - to 3,000 taka (33 euros). Some unions had demanded 5,000 taka.
Gulshan police chief Nural Alam is reported as saying that protesters had targeted the area's high-end shops, looting the contents and then setting fire to the buildings.
Hundreds of riot police have been deployed, he said, adding that officers had used baton charges and tear gas to try to disperse the crowds.
Mosherafa Mishu, head of the Garment Workers Unity Forum, warned that unless a better offer was forthcoming, workers would continue their strike and organise "a militant movement" to protest pay and conditions.
Last week, Prime Minister Sheikh Hasina told parliament that garment workers' salaries were "inhuman" and said manufacturers should share profits with the industry's 3.5 million workforce.