More at the LA Times.
Hoping to end the standoff, law enforcement authorities first lobbed "traditional" tear gas into the cabin. When that did not work, they opted to use CS gas canisters, which are known in law enforcement parlance as incendiary tear gas. These canisters have significantly more chance of starting a fire. This gas can cause humans to have burning eyes and start to feel as if they are being starved for oxygen. It is often used to drive barricaded individuals out.