Asia Pacific markets saw losses throughout the region by Monday afternoon, as shares in Hong Kong tumbled amid worsening tensions in the city.

Chinese mainland markets chalked up losses by the close: The Shanghai composite was down 1.83% to 2,909.07 and the Shenzhen composite declined 2.26% to 1,611.44. The Shenzhen component index lost 2.17% to 9,680.57.

In Hong Kong, the Hang Seng index was deep in negative territory, declining 2.62% by the close as political turmoil in the city worsened. At least two protesters were said to be injured when local police opened fire on Monday at mass demonstrations. Over the weekend, three pro-democracy lawmakers were arrested.

Sectors across the board in the Hang Seng index tumbled, including property developers, tech, financial, as well as gaming stocks.

Japan's Nikkei 225 reversed early gains to trade down 0.26% to close at 23,331.84 while the Topix index edged down to 1,704.03.

South Korea's Kospi fell 0.61% to close at 2,124.09 as major chipmaker SK Hynix slid 1.22%.

In Australia, the benchmark ASX 200 defied the general downward trend in the region and rose 0.72% to 6,772.50.

MSCI's broadest index of Asia-Pacific shares outside Japan fell 1.17%.

On the earnings front, Singapore's DBS Bank reported a stronger-than-expected rise in its third-quarter net profit, which jumped 15% year-on-year to 1.63 billion Singapore dollars ($1.19 billion). Its third-quarter net interest income was up 8% to $2.46 billion Singapore dollars.

DBS shares in Singapore were down 0.34%.