France has declared a national state of emergency and has closed its borders after scores of people were killed in multiple gun and bomb attacks in Paris.

At least 100 people are reported to have died at the Bataclan concert hall in central Paris.

Gunmen took many hostages there before being overpowered when police stormed the building.

Others died in a reported suicide blast near the Stade de France and gun attacks on city centre restaurants.

Paris residents have been asked to stay indoors and about 1,500 military personnel are being deployed across the city.

The deadliest attack appears to have targeted the Bataclan concert hall, with unconfirmed reports saying that concert-goers were being shot one by one. Police sources told AFP news agency that more than 100 people had died there.

Speaking at the concert hall, President Francois Hollande said the attackers would be fought "without mercy".

At least three gunmen are reported to have been killed at the venue.

Other attacks hit Le Petit Cambodge restaurant and nearby Le Carillon in the 10th district, where a BBC reporter said he could see 10 people lying on the road, either dead or seriously injured.

And an eyewitness told Liberation newspaper that he had heard more than 100 rounds being fired at La Belle Equipe cafe in the 11th district.

French President declares state of emergency, closes borders

In a televised address, French President Francois Hollande said he is declaring a state of emergency, which includes the closure of the country's borders.

"Terrorists want us to be scared. In the face of terror we must be united. We will vanquish these terrorists," he said.

Mr Hollande said military personnel were being deployed around Paris and that people should have faith in the security forces.

President Obama reacts

President Barack Obama declared Friday that the day’s terrorist attacks on Paris were an "an attack on all of humanity and the universal values that we share,” promising the full support of the United States for its longtime ally.

"We stand prepared and ready to provide whatever assistance the government and the people of France need to respond,” Obama said. "We are going to do whatever it takes to work with the French people and nations around the world to bring these terrorists to justice.”

"This is a heartbreaking situation,” Obama continued. "And obviously those of us here in the United States know what it’s like. We’ve gone through these kinds of episodes ourselves.”

President Obama refused to speculate on the identity of those responsible for the attack, and the Department of Homeland Security said it was monitoring the situation. "At this time, there is no specific or credible threat to the United States,” the agency said in a statement.

Germany's Merkel says deeply shaken by attacks in Paris German Chancellor Angela Merkel said early on Saturday that she was deeply shaken by a series of attacks in Paris that French media said had killed at least 60 people. "I am deeply shaken by the news and pictures that are reaching us from Paris. My thoughts in these hours are with the victims of what appears to be a terrorist attack, as well as with their relatives and all people in Paris," she said in a statement. "The German government is in contact with the French government and has passed on a message of sympathy and solidarity from the German people," Merkel added.