According to Gazeta.ru, access to most central streets of Minsk has been restricted by 10 am Minsk time:

[...] Kirova St. and Prospekt Marxa are blocked: cars aren't allowed there. Also, a number of government buildings have been cordoned off by the police. City officials explain that these restrictions are caused by the threats of terrorist acts. They ask people not to use cars when getting to the city center and, if possible, empty backyards of residential building of cars, too.

(Update here.)