What just happened? Secure messaging app Telegram was recently hit with a distributed denial of service (DDoS) attack that its founder blames on the Chinese government.

On Wednesday, the official Telegram Messenger Twitter account posted that users in the Americas and other countries may be experiencing connection issues as a result of the powerful DDoS attack.

Company founder Pavel Durov later replied to the tweet, revealing that the IP addresses were coming mostly from China. He noted that the attack coincided with the protests in Hong Kong, where people are using encrypted apps such as Telegram to avoid state surveillance. They are also covering their faces to stop facial recognition cameras, and are avoiding using public transport cards, which can be linked to their identities.

Mass demonstrations have been taking place in Hong Kong over the last few days, as hundreds of thousands of protesters oppose government plans to introduce legislation that would allow extraditions to China, giving its neighbor more authority over the country.

Bloomberg reports that encrypted peer-to-peer messaging services Telegram and Firechat are now two of the top-trending apps in Hong Kong’s Apple store.

According to the South China Morning Post, an administrator of a large local Telegram group was arrested earlier this week for allegedly conspiring to commit a public nuisance.

Telegram Tweeted that the DDoS attack had stabilized by 8 pm Hong Kong time on Wednesday. It added that the attack was designed only to overload the servers with extra work and that users’ data was safe.

Back in 2015, Telegram was crippled in Asia by a cyberattack just as China was initiating a crackdown on human rights lawyers.