A Paris city hall official said four gunmen systematically slaughtered at least 87 young people attending a rock concert at the Bataclan music hall. Anti-terrorist commandos eventually launched an assault on the building. The gunmen detonated explosive belts and dozens of shocked survivors were rescued.Some 40 more people were killed in five other attacks in the Paris region, the city hall official said, including an apparent double suicide bombing outside the national stadium, where Hollande and the German foreign minister were watching a friendly soccer international. Some 200 people were injured.The coordinated assault came as France, a founder member of the US-led coalition waging air strikes against Islamic State fighters in Syria and Iraq, was on high alert for terrorist attacks ahead of a global climate conference due to open later this month.Paris Public Prosecutor Francois Molins said the death toll was at least 120. His spokeswoman said eight assailants had also died, seven of whom had blown themselves up with explosive belts at various locations, while one had been shot dead by police."The terrorists, the murderers raked several cafe terraces with machine-gun fire before entering (the concert hall). There were many victims in terrible, atrocious conditions in several places," police prefect Michel Cadot told reporters.After being whisked from the soccer stadium near the blasts, Hollande declared a nationwide state of emergency - the first since the end of World War Two - and announced the closure of France's borders to stop perpetrators escaping.The Paris metro railway was closed and schools, universities and municipal buildings were ordered to stay shut on Saturday. However some rail and air services are expected to run."This is a horror," the visibly shaken president said in a midnight television address to the nation before chairing an emergency cabinet meeting.He later went to the scene of the bloodiest attack, the Bataclan music hall, and vowed that the government would wage a "merciless" fight against terrorism.All emergency services were mobilized, police leave was canceled, 1,500 army reinforcements were drafted into the Paris region and hospitals recalled staff to cope with the casualties.The prosecutor's spokeswoman said she could not say whether any gunmen were still at large.Radio stations broadcast warnings to Parisians to stay home and leave the streets and urged residents to give shelter to anyone caught out in the street.The deadliest attack was on the Bataclan, a popular concert venue where the Californian rock group Eagles of Death Metal was performing. The concert hall is just a few hundred meters from the former offices of the satirical weekly Charlie Hebdo, target of a deadly attack by Islamist gunmen in January.Some witnesses in the hall said they heard the gunmen shout Islamic chants and slogans condemning France's role in Syria."We know where these attacks come from," Hollande said, without naming any individual group. "There are indeed good reasons to be afraid."HIGH ALERTFrance has been on high alert ever since the attacks on the Charlie Hebdo newspaper and a kosher supermarket in Paris in January killed 18 people.Those attacks briefly united France in defense of freedom of speech, with a mass demonstration of more than a million people. But that unity has since broken down, with far-right populist Marine Le Pen gaining on both mainstream parties by blaming immigration and Islam for France's security problems.It was not clear what political impact the latest attacks would have less than a month before regional elections in which Le Pen's National Front is set to make further advances.The governing Socialist Party and the National Front suspended their election campaigns. Ex-president Nicolas Sarkozy, now leader of the main conservative opposition party, said, "The terrorists have declared war on France" and backed the state of emergency and border closure.Hollande canceled plans to travel to Turkey at the weekend for a G20 summit. He called an emergency meeting of his national security council for 9 a.m. (0800 GMT) on Saturday.US President Barack Obama and German Chancellor Angela Merkel led a global chorus of solidarity with France and UN Secretary-General Ban Ki-moon condemned the "despicable attacks" and demanded the release of the hostages.Julien Pearce, a journalist from Europe 1 radio, was inside the concert hall when the shooting began. In an eyewitness report posted on the station's website, Pearce said several very young individuals, who were not wearing masks, entered the hall during the concert, armed with Kalashnikov assault rifles and started "blindly shooting at the crowd.""There were bodies everywhere," he said.The gunmen shot their victims in the back, finishing some off at point-blank range before reloading their guns and firing again, Pearce said, after escaping into the street by a stage door, carrying a wounded girl on his shoulder.Toon, a 22 year-old messenger who lives near the Bataclan, was going into the concert hall with two friends at around 10.30 pm (2130 GMT) when he saw three young men dressed in black and armed with machine guns. He stayed outside.One of the gunmen began firing into the crowd. "People were falling like dominoes," he told Reuters. He said he saw people shot in the leg, shoulder and back, with several lying on the floor, apparently dead.There was no immediate verifiable claim of responsibility but supporters of the Islamic State militant group, which controls swathes of Iraq and Syria, said in Twitter messages that the group carried them out."The State of the caliphate hit the house of the cross," one tweet said.Two explosions were heard near the Stade de France in the northern suburb of Saint-Denis, where the France-Germany friendly soccer match was being played. The blasts were audible on television during the live broadcast.A witness said one of the detonations blew people into the air outside a McDonald's restaurant opposite the stadium.The match continued until the end, but panic broke out in the crowd as rumors of the attack spread, and spectators were held in the stadium and assembled spontaneously on the pitch.Police helicopters circled the stadium as Hollande was rushed back to the interior ministry to deal with the situation.In central Paris, shooting erupted in mid-evening outside a Cambodian restaurant in the capital's 10th district.Eighteen people were killed when a gunman opened fire on Friday night diners sitting at outdoor terraces in the popular Charonne area nearby in the 11th district.The prosecutor mentioned five locations in close proximity where shootings took place around the same time.The Paris carnage came within days of attacks claimed by Islamic State militants on a Shi'ite Muslim district of southern Beirut in Lebanon, and a Russian tourist aircraft which crashed in Egypt's Sinai Peninsula.Earlier on Friday, the United States and Britain said they had launched an attack in the Syrian town of Raqqa on a British Islamic State militant known as "Jihadi John," but it was not certain whether he had been killed.