It is the latest use of chemical irritants deployed by agents in neighborhoods. The incident was also the latest example of increased neighbor resistance to immigration enforcement in Chicago.
While these are effective, it also works to just throw them back. The canisters are hot, so use a work glove, or something to protect your hand, and move quickly, in one swift motion.
https://www.vice.com/en/article/traffic-cones-leaf-blowers-and-other-brilliant-tactics-us-protesters-are-taking-from-hong-kongs-playbook/
While these are effective, it also works to just throw them back. The canisters are hot, so use a work glove, or something to protect your hand, and move quickly, in one swift motion.