One man is in a critical condition in hospital after a shooting during protests in Ferguson over the death of unarmed black teenager Michael Brown.

Missouri State Highway Patrol Capt. Ron Johnson said one person was shot and critically wounded after dozens defied a midnight curfew imposed on the town, NBC reports. He said seven people have also been arrested.

Tensions grew overnight after the Governor of Missouri declared a state of emergency in the St Louis suburb following violence on Friday. Governor Jay Nixon ordered a curfew to run from midnight to 5am beginning Saturday, telling reporters: “This is a test. The eyes of the world are watching.”

Many left the area peacefully before midnight, but around 150 protesters refused to leave before the deadline and police fired smoke bombs and tear gas to disperse the crowd. Johnson defended their use of tear gas as a “proper response”, which he said was done after a police car was shot at.

Highway Patrol Spokesman John Hotz initially said police only used smoke, but later told The Associated Press they also fired tear gas canisters. He said of police efforts: "Obviously, we're trying to give them every opportunity to comply with the curfew."

In pictures: Michael Brown shooting nationwide protests Show all 10 1 /10 In pictures: Michael Brown shooting nationwide protests In pictures: Michael Brown shooting nationwide protests Ferguson, Missouri Protesters ride on top of a car as they gather on West Florissant Avenue in Ferguson, Missouri In pictures: Michael Brown shooting nationwide protests Ferguson, Missouri A protester holds the banner as he joins the protest on West Florissant Avenue in Ferguson, Missouri In pictures: Michael Brown shooting nationwide protests Ferguson, Missouri Missouri Governor Jay Nixon ordered state police to patrol a St Louis suburb, sidelining local police who had clashed with protesters after an unarmed black teenager was killed by an officer In pictures: Michael Brown shooting nationwide protests Ferguson, Missouri People demonstrate in front of a burned down Quik Trip gas station on West Florissant Avenue in Ferguson, Missouri In pictures: Michael Brown shooting nationwide protests New York Thousands of people peacefully gathered in Manhattan's Times Square and Union Square, invoking the rallying cries "hands up, don't shoot" and "I can't breathe," alluding to the deaths of Michael Brown in Ferguson In pictures: Michael Brown shooting nationwide protests New York People protest in front of police officers in New York's Times Square In pictures: Michael Brown shooting nationwide protests New York Protesters march in New York City's Union Square. Vigils are being held across the country for people organizers say died at the hands of police brutality In pictures: Michael Brown shooting nationwide protests Portland, Oregon People take turns speaking in Pioneer Courthouse Square in Portland, Oregon during a vigil for Michael Brown In pictures: Michael Brown shooting nationwide protests Los Angeles, California A protester holds a sign that reads 'Black Lives Matter' as she joins hundreds of demonstrators who gathered in Leimert Park in South Central Los Angeles, California In pictures: Michael Brown shooting nationwide protests Omaha, Nebraska With his hands raised above his head, University of Nebraska criminal justice senior Aron Sanders, of Omaha, Nebraska, kneels in front of the Nebraska State Capitol building, as he and more than 30 others students gathered for a vigil

Johnson said the police operation throughout the night was in response to unrest that erupted near the Red The BBQ Man restaurant in Ferguson, not in response to the curfew.

On Friday, Ferguson police chief Tom Jackson admitted at a news conference that the white officer who shot and killed Brown was not aware the teenager was a suspect in a store robbery, and had in fact approached Brown because “he was walking down the middle of the street blocking traffic".

At around midnight that evening, a large crowd broke into the convenience store that the 18-year-old allegedly robbed the day he was killed and several other stores were also looted, while car windows and the glass around at least one bus stop were smashed.