Police have used smoke bombs to clear demonstrators blocking Interstate 94 in St. Paul during a protest sparked by the recent police killings of black men in Minnesota and Louisiana.

The smoke was used just after midnight when about 200 protesters were in the roadway as police in riot gear slowly moved in. Police said several officers have been injured by rocks, firecrackers and other debris thrown by protesters Saturday night.

A protest leader urged the group to march to the governor's mansion, where protesters have gathered since the fatal police shooting Wednesday night of Philando Castile. The 32-year-old black man was shot during a traffic stop in suburban St. Paul.

The St. Paul Police Department tweeted that arrests have been made during the protest but didn't indicate how many.