The masked mobs on Sunday night smashed banks, stores and bookshops associated with mainland China, trashed government buildings and started fires at the exits of several Mass Transit Railway (MTR) stations as they continued their attack on the city's railway operator for allegedly aiding police in their clearance operations, the South China Morning Post reported.
After a total shutdown for one and a half days, the rail operator reopened half of its stations on Sunday, only to then close four stations and suspend the services of seven lines nd closed the entire network at 9 p.m.
The majority of MTR stations remained closed on Monday morning. The whole system would be shut again at 6 p.m. to "allow more time for repair", the MTR Corporation said.
For the first time, the People's Liberation Army (PLA) barracks in Kowloon East issued a warning in Cantonese on Sunday evening after demonstrators shone laser lights as they walked past the buildings en route to another location.
A yellow flag went up at the top of the building warning the demonstrators as several men in uniform were seen filming the protesters and a floodlight shone on them.
Health officials said that 11 people were admitted to hospitals, with three in a serious condition and five stable. The condition of two was unknown, while one was discharged.
Breaking the anti-mask law - which officially came into force at midnight on Friday - can lead to a maximum fine of HK$25,000 ($3,188), and one year in prison, reports the South China Morninf Post.
Police arrested 13 people between midnight on Friday and Saturday for defying the mask ban.
Most were also charged with participating in an unlawful assembly.
Social media users reported that, on Sunday, among those arrested and unmasked was a 12-year-old girl, but it was yet to be officially confirmed.
( With inputs from IANS )