Chicago police won't say how many protesters they are expecting for the Democratic National Convention in August, but a coalition of groups planning to march on the convention said there will be as many as 40,000.

"Even if it's not an act of violence, and it appears peaceful, but it's a violation of the law, blocking roadways, blocking venues, things of that nature, we will declare mass arrests in those situations and make those arrests," Chicago Police Superintendent Larry Snelling said.

Snelling claimed he cleared the policy with a coalition of groups overseeing the consent decree on police reforms. They are not allowed to comment publicly, but one source said they do not support the mass arrest policy, despite what Snelling says.

Police said as many as 3,000 officers will be specially trained to deal with potential civil unrest, ABC7 reports.