St. Louis County Police Chief disappointed at tonights outcome and said that it was worse than the worst night of riots back in August.

UPDATE: PROTESTS have erupted across the US after a grand jury ruled that the white police officer who shot Michael Brown in Ferguson will not be charged over the unarmed black teen’s death.

The jury’s ruling that there was “no probable cause” to indict Darren Wilson over Brown’s shooting death in the St Louis suburb has caused shock, disbelief and inflamed already simmering racial tensions.

A University City police officer was shot in the arm during the violent protests which saw the town ablaze with fires.

Buildings burn in Ferguson Buildings burn in Ferguson, and police issue instructions to leave the area following riots after a grand jury decision over the death of black teenager Michael Brown. Courtesy: Fox 5

The shooting happened at Canton Avenue and Lamb Avenue and the officer was taken to an area hospital.

The officer is expected to be okay and police are looking for the suspect.

Police made 29 arrests amid the protests and violence, St. Louis County Police said. The police chief, Jon Belmar, said he heard at least 150 gunshots, but authorities said police did not fire at anyone and to his knowledge, police have not caused any serious injuries.

Entire rows of businesses are on fire, including on West Florissant Avenue, a major street in Ferguson. Because there are so many fires and due to gunshots firefighters haven’t been able to reach all of the sites, CNN’s Sara Sidner said.

Rows of cars at a car dealership have also been set ablaze in the nearby city of Dellwood and various police cars have been set on fire.

Many shops that have survived from being set alight have had the windows smashed and were looted.

Governor Jay Nixon has ordered more Missouri National Guard members to Ferguson. The Guard is providing security at the Ferguson Police Department, Nixon’s office said.

Police were forced to fire tear gas at demonstrators amid the chaos.

Protestersalso shut down Interstate 44 and police officers were standing in a line across highway lanes.

Due to reports of gunshots fired into the sky, the Federal Aviation Administration has issued a temporary flight restriction over Ferguson, Missouri until 4.15am on Tuesday morning. Only law enforcement aircraft will be allowed to fly in the zone, and media aircraft are flying just above the zone, the FAA said.

PHOTO: Commissioner Bratton with fake blood thrown on him by Michael Brown protester http://t.co/BHlCN4TpMg pic.twitter.com/x0yWwtBb20 — Eyewitness News (@ABC7NY) November 25, 2014

The violence has gone against the wishes of Brown’s parents, who pleaded for peace.

“This is crazy. I mean, this doesn’t do anything,” one resident told CNN.

She’s worried about how her city would pick up the pieces.

“They’re not going to rebuild. It’s just going to be a ghost town pretty soon.”

Protesters in Ferguson chanted “F--- the police” as news of the ruling filtered through.

Elsewhere in New York’s Union Square, people knocked over barricades set up by the NYPD, and in Times Square Police Commissioner William Bratton was splashed with fake blood during protests.

In Seattle, residents blocked intersections and formed human chains.

Reporter hit in head with rock on air CNN reporter Sara Sidner is hit on the head with a rock, presumably thrown by a protester, while covering building fires in Ferguson. She carries on with her live cross.

Speaking shortly after the ruling, US President Barack Obama said the situation in Ferguson “speaks to broader challenges that we still face as a nation”.

“We need to recognise that this is not just an issue for Ferguson, it is an issue for America,” he said.

He said “a deep distrust exists between law enforcement and communities over colour” but progress would not be made by vandalising property or smashing car windows.

In a statement, Michael Brown’s family said they were “profoundly disappointed’ in the grand jury decision.

“We ask that you channel your frustration in ways that will make a positive change,” they said.

Brown family statement: "Let's not just make noise. Let's make a difference." #Ferguson pic.twitter.com/f8eAQ4AEM2 — Only In Boston (@OnlyInBOS) November 25, 2014

The dead teenager’s devastated mother, Lesley McSpadden, screamed and sobbed after the ruling was handed down.

Shortly after the jury’s ruling was delivered, new photos were released of Officer Darren Wilson’s injuries following his altercation with Michael Brown.

The images had been presented to the grand jury.

Officer Darren Wilson told the grand jury that Michael Brown punched him in the face when he drove back to him after identifying him as a possible suspect in a shop theft, according to documents released by St. Louis County Prosecuting Attorney Robert McCulloch.

He said he tried to get out of his cruiser, but Brown slammed the door shut twice and hit him with his fist.

“I felt that another of those punches in my face could knock me out or worse,” Wilson said. “... I’ve already taken two to the face and I didn’t think I would, the third one could be fatal if he hit me right.”

Bob McCulloch said the evidence was presented to the US grand jury in an organised and credible fashion. More than 70 hours of testimony was heard from 60 witnesses, he said.

Earlier, Missouri Governor Jay Nixon urged tolerance, respect and restraint ahead of the announcement by the Ferguson grand jury.

As Nixon spoke, crowds of protesters gathered outside the Ferguson police department, chanting: “Indict that cop!” and “No justice, no peace!”

Angry demonstrators formed a human chain across an intersection, blocking vehicles from getting through, CNN reported.

Nixon told a media conference that authorities were working to “protect lives, protect property and protect free speech”.

He said state and local law enforcement were working hand-in-hand. The National Guard was on hand at critical facilities, he said.

If I wanted to turn protests violent, I'd fill the streets with police then announce the decision late at night. Oh, already done… #Ferguson — Zach Green (@140elect) November 25, 2014

Regardless of the outcome, this entire process has been a farce, inside a cruel joke, wrapped in an insult. @VanJones68 #Ferguson — Van Jones (@VanJones68) November 25, 2014

St. Louis County Executive Charlie Dooley said either way, the decision was going to cause trauma and conflict.

“Now is the time to show the world that we can act without being destructive”, he said.

He urged people to think with their heads, and not with their emotions.

“I do not want people in this community to think they need to barricade their doors and take up arms,” he said.

This isn't a trial. It's a decision about whether shooting an unarmed person is worth a trial. That should be an easy "yes." #Ferguson — Steve Marmel (@Marmel) November 25, 2014

I don't care if Michael Brown took some cigars -- it's not the point! #Ferguson — Nancy Grace (@NancyGraceHLN) November 25, 2014

As they awaited today’s decision, the family of Michael Brown asked for four-and-a-half minutes of silence before protests begin.

The time period is a reference to the approximately four hours the teen’s body lay in the street after he was shot.

Police only arrived at the scene of the shooting 90 minutes after the teen was gunned down, an investigation by the St. Louis Post-Dispatch found.

When a hearse later arrived, an angry crowd had gathered and it was too dangerous to get the body, authorities said, and a SWAT team was called in.

The shooting triggered riots and looting that captured international attention, and police responded with armoured vehicles and teargas.

Many in the area thought a grand jury decision on whether to charge Wilson with a crime would be announced on Sunday, based partly on a stepped-up police presence in the preceding days, including the setting up of barricades around the building where the panel was meeting.

Downtown STL Inc, a St Louis civic group that promotes downtown businesses, told members in an email on Saturday that the grand jury would reconvene on Monday to continue deliberating. The email did not explain how the group knew that.

Benjamin Crump, an attorney for Brown’s family, said they are frustrated the prosecutor didn’t charge Wilson himself, or at least suggest a charge to grand jurors.

As it is, “you don’t have any direction, you’re just putting all the evidence out there and you’re going to let them figure it out and they can make up their own minds,” Mr Crump said. “You know, it just boggles the mind why he thinks this is fair.”