People in Hong Kong fear that internet access in the city may become more like that in mainland China, after the city invoked a colonial-era emergency law today to ban face masks at public gatherings.

On Friday (Oct. 4), Hong Kong chief executive Carrie Lam announced that the ban would take effect from midnight tonight.

Protesters, who initially took to the streets against a now-shelved extradition bill and have since moved on to broader demands for democratic rights, are already calling for yet another weekend of protests against the ban on face masks. Protests will enter a fourth month on Oct. 9. But, it’s feared that Lam’s use of the Emergency Regulations Ordinance (ERO) may be a prelude to further restrictions, not least on Hong Kong’s communication networks.

The ERO is a colonial-era law dating to 1922, and gives the government sweeping powers. The government can “make any regulations whatsoever” that it considers to be in the “public interest” if faced with “an occasion of emergency or public danger.” Possible measures may include shutting down communication networks, censoring publications, and entering and searching private premises without a warrant.

Lam is under increasing pressure to quell the protesters, who provided a grim alternative narrative to China’s 70th anniversary celebrations on Oct.1. The protesters chanted anti-Beijing slogans and clashed with police, who shot a teenage protester saying that he tried to carry out a “riotous attack” on officers.

Soon after the face-mask ban was announced, LIHKG, the de facto online headquarters of Hong Kong’s protesters, began to urge people to download virtual private networks(VPN). VPNs are used to circumvent internet controls, such as blocked or blacklisted websites. Facebook and Twitter, for example, are not available in China, but under the “one country, two systems” framework, people in Hong Kong enjoy greater freedom to roam the worldwide web than on the mainland. Hong Kong has had free access to the internet, so VPNs weren’t a hot topic of discussion among the city’s internet-users.

A post titled “Buy VPN! Buy VPN! Buy VPN!” by LIHKG-user “Blooddy” on Oct. 4, had 675 comments within a short time, and became the most discussed topic on the website’s political affairs channel. “Soon, LIHKG and Telegram could be blocked. VPNs are the only hope we have, please purchase one when the tools are still available!” Blooddy wrote.

Another user, “data.guy,” who claimed to be a Taiwanese resident of Hong Kong, also urged LIHKG-readers to get VPNs before midnight. In a reference to the face mask ban, data.guy wrote, “The emergency laws will also be effective after midnight, and it’s really hard to say whether the internet will be disturbed.”

This is not the first time Hong Kong has had such fears. In late August, the Hong Kong Information Technology Federation, a trade organization whose members include Microsoft and IBM, issued a strongly-worded statement to voice its concerns. It was in response to a statement from Lam that left open the possibility the government would use emergency powers to quell the protests. The trade body said, “Any such restrictions, however slight originally, would start the end of the open internet of Hong Kong, and would immediately and permanently deter international businesses from positing their businesses and investments in Hong Kong.”