After Orlando, people are using the rainbow filter to change their profile pictures

Up to 50 people are thought to have been killed and another 53 injured in what police called a "domestic terrorism incident" at an LGBT nightclub in the early hours of Sunday in Orlando, Florida.

A man identified as 29-year-old Florida resident Omar Mateen entered the Pulse nightclub at around 2am and fired indiscriminately before a hostage situation developed. The gunman was killed when police stormed the premises.

The incident is the worst mass shooting in US history and Florida has declared a state of emergency.

Full details of what happened are yet to emerge.

Mateen's family are from Afghanistan but he is a US citizen. His father has spoken to the media, saying that he believes his son was motivated by homophobia. Police said Mateen called 911 to pledge his allegiance to Isis just before the attack.

While the LGBT community mourns for what appears to be a targeted attack, people around the world have been offering messages of sympathy and support using hashtags such as #prayforOrlando, #prayforPulse and #stophatenotlove.

The fact that this is the worst attack on LGBT freedoms in the Western world in recent history has led many people to change their profile pictures on social media to rainbow flags or use Facebook's rainbow filter.

Pulse nightclub's Facebook page has also become a focal point for people to express their feelings.

Since the events of last night, it has been flooded with rainbow posts and comments from all over the world designed to show the victims and their families that they are in all our thoughts:

More: Orlando shooting: 50 people killed in 'terrorist' attack on gay nightclub Pulse