KYIV, Ukraine (AP) — A human rights group in Belarus said Thursday that more than 50 people have been detained in the wake of a shootout that left an opposition supporter and a KGB officer dead.

The Viasna group said the detentions appeared to be connected to comments made on social media about the incident. It said those arrested face charges of insulting government officials and inciting “social enmity,” which carry sentences of up to 12 years in prison.

Belarusian authorities reported the incident on Tuesday night, alleging that “an especially dangerous criminal” opened fire on security officers after they showed up at his apartment looking for “individuals involved in terrorist activities.” Authorities said one of the KGB officers was killed and the perpetrator was killed by return fire.

A Belarusian tech news website, Dev.by, on Thursday said the dead civilian was an employee of EPAM Systems, a large US-based IT company founded by Belarusians. EPAM last year started a program to train Belarusian IT workers who lost their jobs for supporting the massive protests that broke out against authoritarian President Alexander Lukashenko.

The huge protests came after election officials said Lukashenko won a sixth term in the August 2020 presidential election that the opposition and the West have denounced as a sham.

Lukashenko’s government unleashed a violent crackdown on the protesters, arresting more than 35,000 people and badly beating thousands of them.