More about why the guard is going in. Using a barrage of tear gas and smoke canisters, and firing rubber bullets and deploying hundreds of officers in riot gear to sweep the streets of protesters, the law enforcement officials had the situation largely under control by the time the curfew began at midnight. Protesters said that the police acted without provocation. But at a news conference about an hour into the curfew, Ronald S. Johnson, the Missouri Highway Patrol captain brought in by the governor