On Saturday, Missouri Governor Jay Nixon declared a state of emergency and ordered a curfew in the city of Ferguson.

The governor was responding to a week of protest in the city, after a police officer shot and killed 18-year-old Michael Brown on Aug. 9.  The decision followed a night of unrest with sporadic looting late in the evening, after hundreds of people had gathered to peacefully protest the shooting.

“We will not allow a handful of looters to endanger the rest of this community,”said Governor Nixon at a Ferguson news conference. “If we’re going to achieve justice, we must first have and maintain peace.”

The curfew begins Saturday at midnight until 5 a.m, said Capt. Ronald S. Johnson, the Missouri Highway Patrol commander whose officers have overseen public security in Ferguson since Thursday, reports the New York Times. He did not say how long the curfew would last.

Some members of the public attending the news conference cried out in protest when the curfew was announced. The curfew would be put in place and enforced, said Johnson, undeterred.

“We won’t enforce it with trucks, we won’t enforce it with tear gas, we will enforce it with communication,” said the captain. “We will be telling people, “It’s time to go home.”

On Friday, the Ferguson Police Department released a video showing the teenager apparently involved in a convenience store robbery. Its release was another sign of discord among the authorities over handling the investigation of the death of Mr. Brown.

The Justice Department asked the Ferguson Police Department not to release the video because of concerns that “it would roil the community further,” said a United States law enforcement official on Saturday. The release “occurred over the objection of federal authorities,” said the official.  The official said federal investigators also had a copy of the video in their possession, “and there were never any plans by the federal investigators to release that copy.”

The family of Mr. Brown and many protesters accuse police of trying to harm the victim’s reputation and divert attention from the officer who killed him. The officer, Darren Wilson, was identified by police for the first time on Friday. Wilson is on administrative leave.