Tear gas inhalation is extremely painful. It is described as feeling like fire going through your nose, sinuses, eyes, and lungs. A person feels like they can't breathe as it creates the sensation of choking. That's why, in 1925, the Geneva Convention made it illegal to use it as a weapon of war.
Though civilians are only watching and sometimes yelling, ICE shoots tear gas at them and a passing car. They fire right at a woman. She had not done anything to threaten them.