MINSK -- Belarusian strongman Alyaksandr Lukashenka has vowed to punish those who have criticized a security officer that authorities say was killed in a shoot-out on September 28 during a raid on a private apartment in Minsk.

The officer of the Committee of State Security (KGB), identified as Dzmitry Fedasyuk, was buried on October 1.

Belarusian authorities claimed earlier that “an especially dangerous criminal” opened fire on security officers after they showed up at his apartment late on September 28 looking for “individuals involved in terrorist activities,” killing Fedasyuk.

The resident of the apartment, who was later identified as Andrey Zeltsar, an employee of the U.S.-based EPAM Systems IT company, was killed in the ensuing shoot-out with officers, authorities claimed.

Lukashenka said on October 1 that "it is too late" for those who praised Zeltsar and criticized both Fedasyuk and the government to remove their posts from social networks, as "we have all their accounts and we can see who is who."

Exiled would-be presidential candidate Valer Tsapkala earlier wrote on social networks that Zeltsar was an example for all Belarusians of how to resist Lukashenka’s oppressive regime.

"Akrestsina is vacant," Lukashenka said, referring to Minsk's notorious Akrestsina detention center, many inmates of which said they were tortured there. "And rascals like Tsapkala think that we will be unable to get them, but they are mistaken. We will not forgive this guy's death."

Meanwhile, the Minsk-based Vyasna (Spring) human rights center said on October 1 that almost 90 people have been detained in Minsk and several other cities after the incident.

According to Vyasna, the arrests were connected to comments on social media about the incident. It said those arrested face charges of insulting government officials and inciting social hatred, which carry sentences of up to 12 years in prison.

Belarus was engulfed by protests last year after a presidential election in August -- which the opposition and the West say was rigged -- gave Lukashenka a sixth consecutive term.

In response, the government has cracked down hard on the pro-democracy movement, arresting thousands of people and pushing most of the top opposition figures out of the country.

On October 1, the Supreme Court of Belarus ordered the liquidation of the Belarusian Helsinki Committee, the oldest human rights organization in Belarus.

According to Vyasna, in the last three months 130 nongovernmental organizations have been forcibly closed.