Hollande: Paris attacks were an act of war by Islamic State militants
French President François Hollande was among people who heard blasts at Stade de France on Friday.
JOHANNESBURG - French President François Hollande has described the deadly attacks in Paris as "an act of war" organised from abroad by the Islamic State group with internal help.
At least 128 were killed when gunmen and bombers attacked restaurants, the Bataclan concert hall and the Stade de France arena across the city last night.
President Hollande will address an extraordinary meeting of parliament on Monday following Friday night's bloodshed.
Hollande has vowed to be ruthless in dealing with the attacks.
"Because France was attacked in shame and violence, France will be pitiless."
WATCH: French President François Hollande Addresses the Nation
The French president was among thousands of people who heard one of the blasts from a double suicide bombing at the Stade de France during a friendly soccer international.
A minute's silence will be held prior to this weekend's European and football league matches in honour of the victims.
At the same time, residents are being urged to stay indoors amid a national state of emergency.
Earlier today, the Islamic State released an undated video threatening to attack France.
The group's foreign media arm al-Hayat issued the threat through a militant who called on French Muslims to carry out attacks.
There's no clarity as to when the video was recorded.
Meanwhile, US President Barack Obama has described the attacks as an outrageous attempt to terrorise innocent civilians.
Obama said, "Once again we've seen an outrageous attempt to terrorize innocent civilians. We stand prepared and ready to provide whatever assistance that the government and the people of France need."
He added that, "Those who think that they can terrorise the people of France or the values that they stand for are wrong."
German chancellor Angela Merkel says her country will do everything it can to hunt down the perpetrators.
She says Germany stands united with France to defend European values.
The Kremlin has released a statement saying this tragedy demands that the world unite in the fight against terrorism.
WATCH: Over 120 killed in Paris terror attacks
World leaders responded with shock and pledges of solidarity for France following the attacks, though there was little action any could immediately take.
The United Nations Security Council issued a statement condemning " barbaric and cowardly terrorist attacks" involving assailants using guns and bombs on several venues, including the national sports stadium and a major music venue.
Divided on many issues, including on the war in Syria that has fueled Islamist violence, the United States and Russia both voiced their support in messages to President Hollande.
Meanwhile, people around the world have taken to social media to express their shock, outrage and support for the victims, with some using the hashtag #PrayforParis.
Images of a darkened Eiffel tower are also being shared.