CHICAGO (CBS) — Naperville is cleaning up and boarding up after protests Monday night turned violent, including an explosive device being thrown at police.

CBS 2 Investigator Dave Savini witnessed some of the violence firsthand as looters and vandals swept through downtown Naperville including a barber shop, a remodeling company, Mod Pizza, retail outlets, the Red Arrow Taproom and more.

One man was punched in the face at the heart of Naperville’s main intersection.

As nightfall came it was clear the peaceful protesters were gone, and another wave of people with a different agenda swooped in. Some members of the crowd turned their efforts toward destruction and personal financial gain and started looting. Some stores were broken into right in front of heavily armed officers.

Savini saw looters in Pandora, but when he approached them, they took off. Juveniles were breaking into stores and smashing windows.

Some looters tried to damage Chase Banks, throwing large rocks or bricks inside, trashing two ATMs. AFter destroying the ATMs, they continued down the street and started to damage more businesses, including breaking a window and stealing a fully clothed mannequin at White House Black Market.

Quigley’s Irish Pub took matters into their own hands. In addition to boards, some of their patrons volunteered to stand guard.

“They blew out windows all the way around,” said Quigley’s patron John Burke.

Like some of the looters, they too were armed with baseball bats, trying to protect against any damage.

Several officers suffered injuries from the explosion. In all 30 businesses were vandalized, including guns stolen from a gun store. There were 11 arrests.

A peaceful gathering for residents is planned for Tuesday night.