TV AND WEB RESTRICTIONS~**CBS - DIGITAL USE ONLY, NO BROADCAST USE WORLDWIDE, NO ACCESS AUSTRALIA BROADCASTER WEBSITES. NO ACCESS JAPAN. NO ACCESS ABC AMERICA, FOX, UNIVISION, TELEMUNDO, BBC AMERICA, NBC, OR THEIR DIGITAL/MOBILE PLATFORMS. NO ACCESS MISSOURI MEDIA MARKET

Police enforced a curfew against protesters angry at the shooting death of a black teenager by a white police officer in Ferguson, Missouri, clearing the streets of demonstrators early on Sunday during a tense standoff.

"You must disperse immediately," a law enforcement official warned over a loudspeaker as police slowly moved down the street where dozens of demonstrators remained after the curfew took effect at midnight local time.

Officers were equipped with gas masks and full-length shields, standing among armored vehicles.

A short time later, officers began firing cannisters toward the crowd, which a state Highway Patrol spokesman said dispersed smoke, not tear gas. But St. Louis alderman An