Justin Bieber suffers concussion after hitting his head backstage in Paris

PUBLISHED: 13:56 EST, 30 May 2012 | UPDATED: 22:14 EST, 31 May 2012

Bieber mania swept through Oslo, Norway, over the course of three days and left 49 teenage girls injured amongst the crazed hysteria.

But it seems they weren't the only ones getting hurt - after the Biebster was left injured himself.

The pop prince was left concussed after running into a glass wall backstage at a secret Paris gig the following day.

Justin, who is now 'taking it easy', tweeted his fans: 'just smacked my head and needed some water. all good.

Raucous: At least 49 Justin Bieber fans were left injured in Oslo, Norway, after mass crowds went wild to see the pop star perform, yesterday

What riot scene? Justin seemed in good spirits as he arrived in Paris, France, earlier today, and was bombarded by fans again

'im (sic) Canadian. we are tough. lol. its all good. just gotta take it easy the rest of the night. back at it again for u guys tomorrow. thanks.

'gonna eat, rest, get some sleep and tomorrow Im back at it. The show must go on! Love yall. We got this.'

He later joked: 'i will see u again Glass. I will have my revenge. BIEBER vs GLASS. MGM LAS VEGAS 2013. lol. #GottaLaughAtYourself.'

The incident during the gig, with Justin managing to complete his set, before passing out briefly in the dressing room afterwards.

The news comes as the mayor of Oslo, where Justin performed earlier this week, reportedly launched an investigation into the star's pandemonium and issued a statement on the situation.

Get back: One of Justin's bodyguards tries to shield the young pop star from his fans as he moves through the airport

Ouch! Things went badly for Justin in Paris too, after he was knocked out when he ran into a wall of glass during his concert

Getting a close up: Justin and his entourage blocked a young female fan from touching him as she was pushed away

Soft side: Justin was happy to pose for a quick photograph once he realised the girl wasn't trying to attack him

Mayor Stang said: 'I have already called on the Emergency Planning Agency to examine the entire event from the planning stage to its implementation.

'We have to find out what went wrong and why it happened.'

The local police force were almost forced to issue a state of emergency as tens of thousands of screaming Beliebers swarmed upon the streets of the capital city.

As more and more fans descended on the city, traffic was left gridlocked as the girls stampeded through the normally quiet roads.

According to TMZ.com, the mayor fell victim to the onslaught of manic fans and had to take shelter behind a tree in order to avoid getting trampled all over.

The running man: As Beliebers rush towards their idol, a bodyguard makes a swift move to try and block them off

Mr popular: The Boyfriend singer was unable to walk through Paris wihthout getting stopped by eager fans

Mr popular: The Boyfriend singer was unable to walk through Paris without getting stopped by eager fans

I love you: Justinn hinted that he may be hooking up with Kanye West while in the city of love

Meanwhile, with the carnage left firmly behind him in Oslo, Justin, 18, moved on to his next destination and arrived in Paris.

After tweeting: 'PARIS Here we Come. #BELIEVE', the scenes which he had left just 24 hours ago seemed to be repeating in the French capital.

The Boyfriend singer said: 'thanks to all the fans at the airport and at the hotel. amazing welcome. happy to be here and look forward to some surprises. Je t'aime'.

It appears that accumulating injuries is a prerequisite for Bieber fans, as a young Parisian girl came close to falling foul of her idols bodyguards.

As Justin arrived in Paris, a female fan tried to grab a piece of him in order to get a photograph with the star.

Naughty boy: Justin, pictured yesterday in Oslo, Norway, caused a lot of trouble when his fans got out of control

Health and safety: the mayor of Oslo is launching an investigation into the event after 49 girls were injured and the city was overrun

However, the well protected teen was promptly pulled out of the line of fire as a bodyguard pushed her away.

Justin hinted that he may have hooked up with his friend and rap superstar Kanye West after tweeting: '@kanyewest #biebsinparis'.

Mr West is in the city ahead of his Watch The Throne concert with Jay-Z at Paris Bercy.

Taking over: Justin Bieber fans took over Oslo, Norway, when they heard the star was due to perform a free concert in the capital

The pint sized star will be hoping his Parisian fans will not be taking police by surprise as they did in Norway.

In Oslo, fans assembled outside the Grand Hotel on Karl Johans Gate, but the Boyfriend singer was actually staying at the nearby Royal Christiania Hotel, which prompted a mass stampede when the girls found out.

Justin appeared briefly to wave at his followers but was later forced to evacuate the hotel because of security fears.

You make me wanna shout: The 18-year-old screams out to the crowds of female fans from the safety of his hotel window

Cancelled: Justin Bieber's press conference had to be called off today because the fans were going crazy

Here's looking at you kid: The Canadian pop star takes a stance at his floor length window and continues to wave at fans

Yesterday, the police admitted that they had lost all control of the huge number of fans and were unable to cope with the sheer size of the group.

It was announced on TV, last night, by Norwegian Broadcasting (NRK) that Bieber would be playing a free concert at 9.20pm from a floating stage next to Oslo's Opera House.

Armed with the new information, around 15,000 fans swamped the venue and scrambled on to the roof of the opera house waiting to see Justin perform.

Follow that car: Thousands of girls crowded the roads and stopped traffic from passing through in a timely fashion

Total gridlock: The female fans blocked off the streets with the sheer size of their number

Crazy gang: Justin's Beliebers fled the square once they found out that he was not staying at the rumoured hotel

The local authorities issued a warning that the roof was already over capacity and nobody else should try and get near the event, but the words fell on deaf ears.

Concerns over the girls safety and the fact that they have no toilets, food or drink readily available prompted police to contact the teen heartthrob.

They reportedly told Justin to take to the stage immediately or they would issue a state of emergency, after many females began fainting in the crowd.

Traffic was unable to move through the area because all the roads around the venue were filled with people.

Girls gone wild: The young fans ran screaming towards the nearby Royal Christiania Hotel, where Justin was staying

Peace and love: Bieber took to twitter to ask his fans to be calm and listen to the police orders

Justin told NRK: 'The concert should have been held somewhere else than on the Opera roof', and blamed his record label for the poor planning.

He also took to twitter to speak to his near 23 million followers and said: 'NORWAY - please listen to the police. I dont want anyone getting hurt. I want everything to go to plan but your safety must come first...

'...for the show to happen u must all listen to the police. we are all concerned for your safety and i want what is best for u. please listen'.

Calm before the storm: Police thought they had everything under control but the girls soon broke loose from the barriers

Under control: The police eventually regained power of the city and set up more barriers to hold back screaming girls

The singer continued: 'and tonight we will have some fun. love you and im excited to see you all. NORWAY...THANK YOU FOR HAVING ME! #BELIEVE'.

Justin did eventually take to the stage and he didn't leave his loyal followers disappointed after he performed six songs in total, debuting four new ones.

He tweeted: 'been almost a year since ive done that. missed the stage. that was fun. #BELIEVEtour is gonna be epic'.

He later added: 'i missed performing for you. Im glad I get to do it again. I MISSED ALL OF YOU! WE ARE BACK! #BELIEVE. #ILOVEMYBELIEBERS'.