Twitter accounts linked to jihadists are celebrating the attacks in Paris According to the SITE Intelligence Group tracking militant sites, Twitter posts attributed to jihadist supporters are speculating which group may be responsible. Many users expressed belief that the Islamic State group could be behind the carnage. They used Arabic-language hashtags that translated to "Paris on fire" and "Caliphate state strikes France." SITE says that accounts also circulated pictures of the attacks, and one pro-IS channel accused France of sending warplanes to bomb Syria and says "today it drinks from the same cup." More hostages A French police official says top government officials including President Francois Hollande were headed to the Bataclan concert hall where hostages were taken. Another official said at least 100 people died inside the hall. A police assault on the venue finished early Saturday, leaving at least two attackers dead, officials said. The officials were not authorized to be named because operations were ongoing. the country in state of emergency A French government official says the country's state of emergency has gone into effect and that President Francois Hollande is cancelling his trip to the G-20 meeting in Turkey. Hollande was due to leave Saturday for the meeting in Turkey, which was to focus in large part on growing fears of terrorism carried out by Islamic extremists. The official, who was not authorized to be named, said the government will hold a defense council meeting in the morning. World leaders have expressed shock at the violence in Paris. German Chancellor Angela Merkel says she is "deeply shaken by the news and pictures that are reaching us from Paris." The German leader issued a statement saying her thoughts were with the victims "of the apparent terrorist attack." The Secretary-General of the NATO alliance says he is "deeply shocked by horrific Paris attacks."