Video of the incident on January 22 showed a man engulfed in a fiery ball rolling on the ground for several seconds, with what appears to be a gas canister nearby.
One video that captured the incident shows police officers trying to cover him with a blanket to extinguish the fire.
The incident took place near the building that houses the government, parliament, Minsk city administration, and the City Council.
Minsk city administration spokeswoman Natallya Hanusevich said in a statement that the incident was being investigated.
Interior Ministry spokeswoman Volha Chamadanava added in a statement that “at this point, it is not possible to give detailed information on the incident.”
Crisis In Belarus
Read our coverage as Belarusians take to the streets to demand the resignation of President Alyaksandr Lukashenka and call for new elections after official results from the August 9 presidential poll gave Lukashenka a landslide victory.
“The investigative group was dispatched to the site. As soon as we know all the circumstances around the incident, we will let the public know,” Chamadanava said.
Health Ministry officials said that the man, whose identity was not disclosed, is unconscious and had burns over 50 percent of his body.
Belarus has been gripped by a political crisis since August 9, when officials declared Alyaksandr Lukashenka, who has run the country with an iron fist since 1994, the winner of a presidential election.
Opposition figures called the vote rigged, with thousands taking to the streets to protest on an almost daily basis.
Lukashenka’s declaration of victory has not been recognized by Western nations, many of whom have slapped him and other Belarus officials with sanctions for their violent crackdown on the dissent.