Facebook has changed its safety check feature to have a specific Paris focus following the terrorist attacks on the French capital.
If the social media app notices a user's device is located in Paris, it will ask them whether they are safe.
The "Safety Check" tool will then notify all the friends of that person that they have marked themselves alive.
Users can also check on a list of friends who may be caught up in the tragedy which unfolded in Paris on Friday night, followed by The Independent live blog here.
Location is determined by the city in which a person uses internet, the city listed in their profile or their last location if they use the Nearby Friends product.
If someone is not in the Paris area, they can select "I'm not in the area."
Twitter followers based in the capital also offered safe refuge to fellow citizens with the hash tag #PorteOuverte, inviting those too afraid to make longer journeys home to stay with them.
The death toll from the attacks, now claimed by radical Islamist terror group Isis, is believed to be more than 120.
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