Eighteen police officers were injured in a Chicago protest

Eighteen Chicago police officers were injured in Friday's protests, the department said in a statement.

At 4:20 pm a large crowd gathered for the protest. Local time, the department said. The statement said that the authorities "are defending the right to security and their first amendment to the peaceful assembly."

The statement said some of the crowd used stones, firecrackers, frozen bottles, and other items to attack officers who saw the statue of Christopher Columbus.

A statement said 18 officers were injured in the attack. Others were taken to area hospitals for further treatment by paramedics, while others were treated at the scene.

According to the statement, about 12 people have been arrested and the police officer could be charged with possession of a battery, mob action, and/or other offenses.

The incident comes two days after three NYPD officials and a senior official were injured in clashes with protesters.

A department official said a 24-year-old woman was arrested for holding a cane while trying to arrest a guard.

"Three officers violently attacked protesters crossing the Brooklyn Bridge," the department said on its certified Twitter page. "Officers were seriously injured. This is not a peaceful protest, it will not be tolerated."