At least five officers were injured. One policeman was hit with a glass bottle and another by fireworks, according to St Paul police.
Image is being defined as iconic and a powerful image of the ongoing struggle between law enforcement and black Americans.
Hundreds of people marched through Times Square in New York City to protest the deaths this week of Philando Castile and Alton.
Five officers were killed in a shooting in Dallas during a protest in response of the tragic deaths of Alton Sterling in Louisiana and Philando Castile in Minnesota.
Shocked family members demanded justice for Castile, a school cafeteria worker, whose mother described him as a law-abiding citizen who kept out of trouble.
The US president paid tributes to the five police officers killed in the deadly sniper attack in Dallas.
Dallas police say the gunman staged a furious ambush-style attack in Dallas at a rally held to protest this week's fatal shooting of two black men by police in other states.
The winners of the 60th annual World Press Photo Contest have been announced. The winning shot was taken by Turkish Associated Press photographer called Burhan Ozbilici, with an image he has simply titled An Assassination in Turkey. Showing Mevlut Mert Altintas shouting after shooting Andrei Karlov, the Russian ambassador to Turkey, at an art gallery in Ankara, Turkey, on December 19 2016.
'The year in pictures' treks across the globe, looking back on the moments that shaped 2016. From the United States presidential race, to demonetisation in India to the refugee crisis, the news has kept pouring in. Here are our top 50 moments from the world.