ARTEMIVSK, Ukraine — An explosion in downtown Kiev, Ukraine, on Friday injured at least two people and ignited fears of new conflict in the city, where protest barricades and tents still stand in the central square months after demonstrations that toppled the government.

Kiev’s deputy police chief said in a statement shortly after the blast that the police had arrested a man who had thrown a grenade toward the Ukrainian House, a convention center. The motive for the attack was not immediately clear.

Clashes broke out the day before when municipal workers and national guard units tried to clear the square of holdout protesters from the February demonstrations that led to the ouster of the president, Viktor F. Yanukovych. The workers abandoned their attempt when a tent caught fire.

The continuing presence of protesters in the square, called the Maidan, has become a source of contention in Ukraine, as well as in neighboring Russia, where the square is often portrayed as a source of anti-Russian feeling and Ukrainian nationalism.