People stranded near Munich during Friday's attack were offered refuge by members of the public through social media.
Nine people were murdered and at least 16 injured by a gunman near the Olympia shopping centre, prompting the closure of transport links across the city. Munich Police have urged people to avoid public places.
In response, hundreds of people on Twitter used the hashtag #OffeneTur - or #OpenDoor - to invite people to stay if they were unable to get home.
Facebook's Safety Check feature was also activated so that people could let friends and family know that they were safe.
It was most recently used in the wake of the Nice attack earlier in this month. People also opened their homes under the hashtag #PorteOuverte during the Nice attack and Paris attacks in November to help people find safety.