A terror probe has been launched in Paris after a man was shot by soldiers while trying to storm the Louvre armed with a machete.
The suspect was shot five times in the stomach and is in a critical condition.
He was shouting 'Allahu Akbar' - Arabic for 'God is the greatest' - according to the Paris prefect.
After being refused entry, he pulled out the weapon and was shot by a soldier, officials have confirmed. A solider is believed to have suffered a head injury.
Streets around the Louvre in the French capital have been evacuated, and it has been branded a 'serious security incident' by the interior ministry.
A second man has been arrested after 'acting suspiciously' close to the scene, but it is not known if he is linked to the attack.
French Prime Minister Bernard Cazeneuve has described the attack as 'terrorist in nature'.
Interior ministry spokesman Pierre-Henry Brandet said the the identity and nationality of the suspect are not yet known. Interior minister Bruno Le Roux has cut short a trip to the Dordogne and is set to visit the injured soldier this afternoon.
An estimated 1,250 people were inside the famous art gallery, home to the Mona Lisa, when the shooting happened. Pictures from inside the museum shows schoolchildren cowering during the emergency lockdown.
Soldiers patrolling as part of France's ongoing State of Emergency stopped the man getting into the building shortly after 9am.
'He was carrying a suitcase and was refused access,' said a police source at the scene. 'The man immediately withdrew a knife, and attacked.
'It was at this moment that a soldier used his weapon to disable the men, who was wounded. The area has been evacuated.'
A spokesman for the military force that patrols key sites in Paris said the four-man patrol of soldiers tried to fight off the assailant before they opened fire.
Benoit Brulon said a soldier who was slightly injured by the attacker was not the solider who opened fire.
The alleged attacker is in a 'serious condition', officials have said.
Michel Cadot, the Paris prefect, said at the scene: 'Emergency workers are currently trying to revive him. He was shot five times in the stomach, but is still alive. A soldier was also injured.'
Mr Cadot said the attack happened at the top of an escalator that leads down into the shopping complex.
He said the knifeman 'appeared to be acting alone', and that the words used pointed to extremist terrorism.
Mr Cadot said the soldier had to 'neutralise the attacker' after the soldier was lightly injured by the assailant.
The suspect's rucksack was searched, but there was no sign of any explosives.
The drama unfolded next to the Carrousel du Louvre - a vast underground shopping centre built into the museum complex.
The huge former royal palace in the heart of the city is home to the Mona Lisa and other world-famous works of art but also a shopping complex and numerous exhibition spaces.
It is always packed with thousands of tourists from all over the world, all of whom have their bags inspected before entry. By 11am, the entire area was shut down, as hundreds of extra soldiers and police flooded into the area.
The Rue de Rivoli running alongside the museum was closed to traffic while trains were being pushed through the Palais Royal-Musee du Louvre metro station without stopping.
The emergency response was filmed on live video app Periscope this morning.
Police union official Yves Lefebvre said the man attacked soldiers when they told him he could not enter an underground shopping mall beneath the Louvre with his bags.
Mr Lefebvre says police found two machetes on the man.
'We've been told to leave - it's very frightening,' said John O'Shea, a 52-year-old Canadian who was with his wife and young son.
'Everybody is talking terrorism, but we really don't know what's going on. Apparently a number of shots were fired.'
A police union official, Luc Poignant, told BFM-TV an attacker assaulted the soldier and that the area was now being evacuated and secured.
Paris is on a high state of terrorist alert following murderous attacks by Islamic State operatives in 2015.
On November 13 2015, 130 people were murdered in a single night of violence which included attacks on the Stade de France, the Bataclan concert venue and cafés and restaurants.
A shop worker who was in the shopping centre at the time of the attack said: 'We heard gunfire and reacted immediately - shutting down the grills in front of the shop, and retreating into the back.'
The 19-year-old man, who asked not to be named added: 'Once the all-clear was given by the police we got out as quickly as possible. I'm on my way home.
'You always hear about the possibility of terrorism, especially in the area around the Louvre, but this was the real thing.'
Anne Hidalgo, the Socialist Mayor of Paris, soon arrived at the scene to praise the 'extreme efficiency' of the soldiers who foiled what could have been a very serious attack.