As it has in many recent global events, social media is playing a large role in the terrorist attacks in Paris.
It is not a claim of responsibility, but an Islamic State supporter used Twitter to express joy over the bloodshed. He tweeted the grim words "Paris is Burning" and used the hashtag #Parisisburning.
That hashtag has been co-opted by supporters of IS to gloat. Tweets containing the Arabic translation of the hashtag also contain photos from the scenes of the attacks. IS supporters have also been using #Prayforparis to show support for and to praise the attacks.
#Parisisburning also has been used by people sharing information on how to help victims, locate friends and family in Paris and express their sympathies.
Facebook activated a safety check that allows people in Paris to check in and mark themselves as safe, which then allows their friends on the social network to see that they are ok.
The U.S. band Eagles of Death Metal, which was giving a concert at the Bataclan concert hall, has been communicating with its fans through its Facebook page, saying it is trying to determine the safety and whereabouts of band members.
Leaders react
French President Francois Hollande has been using Twitter to keep his fellow French citizens up to date on the situation.
Rather than taking the time to run to a television camera or find a microphone, a number of world leaders tweeted their reaction and sympathy. They include British Prime Minister David Cameron, European Union chief Jean-Claude Juncker, and NATO Secretary-General Jens Stoltenberg.
They all expressed their deep shock and solidarity with France.
Several U.S. presidential candidates, including Democrat Hillary Clinton and Republicans Marco Rubio, Ted Cruz, and Ben Carson used Twitter to express their feelings.