PITTSBURGH – (WPXI)- Thousands of protesters gathered in Pittsburgh’s East Liberty neighborhood Monday afternoon. It wasn’t until a few hours later when police said a small group of people split off from the peaceful protest and began to damage businesses in the area. Police said they started to throw rocks and other items at law enforcement, and smoke was thrown after officers gave numerous orders for them to disperse. Pittsburgh Public Safety Director Wendell Hissrich said 9 officers were injured. All officers were evaluated and released from the hospital. Hissrich said least 4 windows were broken, but it doesn’t appear any businesses were looted. Two protesters were transported to hospital with injures that they said they got from bean bags. Hissrich said 20 people were arrested tonight, which include four people who are not from Pennsylvania. Police did clarify that officers deployed smoke and not tear gas.