True. That is not something to be taken lightly. Our next door neighbor had an underground nest in a small bush at the corner of his deck. He waited until dark, poured down some liquid gold and fired it up. He stayed out with it until everything had burned out. Or so he thought. A few hours later his wife came home and told him the bush outside was on fire. Sure enough... the bush was burning. Thankfully he was able to get everything quenched with the hose but thought about how differently things may have gone had his wife not come home later.Probably has something to do with the front porch and potentially the rest of the house and largely on becoming the target of his wife's wrath if he burnt it down.
It might not be a bad idea to flood the hole with water after burning them out.