HONG KONG — Hundreds of thousands of pro-democracy protesters returned to the streets of Hong Kong on Sunday, defying a ban on assembly before being violently dispersed by police tear gas and a water cannon.

A police water cannon filled with stinging blue dye blasted protesters along a major thoroughfare in Kowloon. It also hit a small group standing guard outside a mosque — an important spiritual nexus for the city's largely South Asian Muslim community — leaving bystanders choking and vomiting and eliciting a rare apology from authorities.

Protesters vandalized businesses viewed as supporting Beijing, threw molotov cocktails at police stations, set barricades on fire and smashed up subway stations in chaotic scenes that have become familiar to the city after five months of sustained protest.

A journalist photographs police spraying blue dye from a water cannon in Hong Kong on Sunday. (Kim Kyung-Hoon/Reuters)

The huge turnout, estimated by organizers at around 350,000 and including families, children and the elderly, showed that the movement maintains widespread support in the face of the increasingly violent tactics of protesters and the escalating use of force by police.