CHICAGO (CBS) — Mayor Rahm Emanuel was meeting with community and religious leaders on Monday, to prepare for the backlash when a video showing a white police officer fatally shooting a black teenager is made public.

It was October 2014 when Officer Jason Van Dyke shot 17-year-old Laquan McDonald 16 times on a street in the Archer Heights neighborhood.

A Cook County judge has ordered police to release dashboard camera video of the shooting by Wednesday.

Chicago area pastors have said they are concerned about the video’s potentially inflammatory nature.

“Getting ahead of it, and making sure that we present to the mayor what we expect to happen, I think that’s critical if we’re going to prevent violence from happening in our neighborhoods,” said Rev. Corey Brooks, pastor of New Beginnings Church.

Brooks and other ministers and activists planned to meet with the mayor at 3:30 p.m. Monday to discuss how tamp down the potential for violence after the video is released.

While the city originally planned to appeal the ruling to make the video public – and had argued releasing it could jeopardize an investigation of the shooting – the mayor’s office later said the city would comply with the order.

“We must try to keep this thing as calm as possible, but when the Chicago police take and slaughter a 17-year-old child, you have upset our community,” said Mark Carter, a community activist with the group ONE Chicago.

Carter said the mayor should lead an effort to make sure the officer is indicted, and should also demand the resignation of Police Supt. Garry McCarthy.

Although the mayor initially fought the effort to make the video public, he reversed course last week, and criticized the officer’s actions.

“Police officers are entrusted to uphold the law, and to provide safety to our residents. In this case, unfortunately, it appears an officer violated that trust at every level. As a result, the city’s Independent Police Review Authority promptly sent this case and the evidence to state and federal prosecutors who have been investigating it for almost a year,” he said in a prepared statement last week.

Attorneys for McDonald’s family have seen the video, and said it is shocking and disturbing, and have described the shooting as an “execution.”

“The first shot or two seem to spin him on the ground. He falls down. He’s down on the ground, and for the next 30 seconds or so, in this video, the officer just continues to shoot,” Neslund said earlier this month. “What you see are graphic puffs of smoke rising from Laquan and intermittently his body twitching, in reaction to the shots.”

The city’s police union has said McDonald was slashing tires with a 4-inch knife, and high on PCP, when he refused police orders to drop the weapon. Van Dyke has said McDonald lunged at him. His attorney, Dan Herbert has acknowledged video is graphic, but he said the officer feared for his safety, and the shooting was justified.

“He firmly believed he was in fear for his life and concerned about the life of his fellow officers,” Herbert said last week.

The city agreed to a $5 million settlement with McDonald’s family even before a lawsuit was filed. Van Dyke, a 14-year veteran, has been stripped of his police powers, pending investigations by federal and Cook County prosecutors.

The mayor’s office and police department have not yet said exactly how or when the video will be released.