The anniversary of 18-year-old Michael Brown's death in Ferguson, Missouri, began with a solemn march in his honour and ended in chaotic scenes described as a shoot-out involving two rival gangs and police. One gunman, identified as Tyrone Harris, 18, is in a critical, unstable condition after he was shot at by four plainclothes police officers. The father of Harris told the St Louis Post-Dispatch that his son had been a close friend of Michael Brown.

Shots rang out around 11.15pm as several hundred people gathered on West Florissant Street. St Louis County Police Chief Jon Belmar said that plainclothes officers had been tracking the man, who they believed was armed. Belmar said the man approached the officers, who were in an unmarked police car and opened fire. The officers returned fire from inside the vehicle. They then pursued the man on foot. The chief said the man again fired on the officers and all four fired back.

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Police officers attend to a man lying on the street in Ferguson after being shotRick Wilking/Reuters
Ferguson anniversary police shot man
A police officer holds his service pistol as he takes cover in FergusonRick Wilking/Reuters
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Police officers and bystanders take cover as shots ring out along West FlorissantScott Olson/Getty Images
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People fall to the ground to take cover after shots were fired in FergusonRick Wilking/Reuters
Ferguson anniversary police shot man
A man is loaded into an ambulance after being shot in FergusonRick Wilking/Reuters
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A police unit is parked at outside a looted store in FergusonRick Wilking/Reuters

Before the shots were fired, protesters had been blocking traffic and staging demonstrations outside the Ferguson police department. Demonstrators wore T-shirts with likenesses of Brown or messages such as "Please stop killing us" and "Hands up! Don't shoot!" which became a rallying cry during the sometimes violent protests that followed the shooting a year ago. For the first time in three consecutive nights of protests, some officers were dressed in riot gear, including bullet-proof vests and helmets with shields.

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Amarion Allen, 11, and his mother Amima stand in front of a police line shortly before shots were fired in FergusonRick Wilking/Reuters
Ferguson anniversary police shot man
Demonstrators marking the anniversary of the shooting of Michael Brown march along West Florissant in the driving rainScott Olson/Getty Images
Ferguson anniversary police shot man
Scott Olson/Getty Images
Ferguson anniversary police shot man
A protester yells at officers stationed outside the police department in FergusonRick Wilking/Reuters
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Scott Olson/Getty Images
Ferguson anniversary police shot man
Protesters chant as the rain falls along West FlorissantScott Olson/Getty Images
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Scott Olson/Getty Images
Ferguson anniversary police shot man
Demonstrators stage a die-in on West Florissant in the pouring rainScott Olson/Getty Images
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People pray during a rain storm on the anniversary of the death of Michael Brown in FergusonRick Wilking/Reuters
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A demonstrator holds the head of roasted pig during a protest outside the Ferguson Police DepartmentMichael B Thomas/AFP
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Scott Olson/Getty Images
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A demonstrator, marking the anniversary of the shooting of Michael Brown, stops to take a selfie while protesting along West FlorissantScott Olson/Getty Images
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Demonstrators face off with police during a protest along West Florissant in FergusonScott Olson/Getty Images
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St Louis County Police and Missouri State Highway Patrol troopers stand on guard as protesters march on West Florissant Avenue in FergusonMichael B Thomas/AFP
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A man gestures towards the Ferguson Police DepartmentMichael B Thomas/AFP

Michael Brown's father led a march in Ferguson after a crowd of hundreds observed four-and-a-half minutes of silence. Those who gathered to commemorate Brown began their silence at 12.02pm, the time he was killed, for a length of time that symbolised the four-and-a-half hours that his body lay in the street after he was killed. Michael Brown Sr held hands with others to lead the march, which started at the site where his son was fatally shot by Ferguson officer Darren Wilson on 9 August 2014.

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Michael Brown Sr listens to speakers at the spot on Canfield Street in Ferguson where his son was killed, during a memorial service marking the anniversary of his deathScott Olson/Getty Images
Ferguson anniversary police shot man
The crowd listens to speakers at an event to mark the anniversary of the killing of Michael Brown in FergusonRick Wilking/Reuters
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A partially burned American flag lies on the street near the spot where Michael Brown was killedRick Wilking/Reuters
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Roses lie next to a plaque in the pavement at the spot where Michael Brown was shotScott Olson/Getty Images
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Local residents and volunteers from nearby churches hold hands while praying with one another during a community event hosted by the Convoy of Hope in Forestwood Park in FergusonAdrees Latif/Reuters
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A piece of concrete with "MB" spray-painted on it marks the grave of Michael Brown at St Peter's Cemetery in Normandy, MissouriRick Wilking/Reuters