FERGUSON, Mo. — Missouri National Guard troops entered this battered city on Monday even as an overnight curfew was lifted, the latest in a series of quickly shifting attempts to quell the violence that has upended this St. Louis suburb for more than a week.

In the days since an unarmed black teenager, Michael Brown, was shot to death by a white police officer here on Aug. 9, an array of state and local law enforcement authorities have swerved from one approach to another: taking to the streets in military-style vehicles and riot gear; then turning over power to a State Highway Patrol official who permitted the protests and marched along; then calling for a curfew.

Early Monday, after a new spate of violence, Gov. Jay Nixon said he was bringing in the National Guard. Hours later he said he was lifting the curfew and said the Guard would have only a limited role, protecting the police command post.