Police push Trump inauguration protesters back and fire stun grenades at them

The video transcript describes a tense situation involving protestors and police. Initially, the scene is set with protestors standing and sitting with their hands in the air amidst stun grenades and tear gas. The police respond to protestors throwing missiles, such as rocks and broken cement, by charging to regain control. The transcript highlights the high tensions and the police's strategic response to maintain order.

How did the presence of tear gas affect the situation described?

What was the police's justification for charging the protestors?