Facebook has activated its "Safety Check" function on Sunday for the first time in the United States after a gunman massacred 50 people in a nightclub in Orlando, Florida.

The Safety Check, introduced in 2014, allows Facebook users across the globe to spread the word that they are safe amidst a natural disaster or crisis or manmade issues. It also allows searches for the victim in the affected area.

"Waking up this morning, I was horrified to hear about the shooting in Orlando," said Facebook Chief Executive Mark Zuckerberg on his official account.

"My thoughts and prayers are with the victims, their families and the LGBT community."

Notably, this step comes after a gunman stormed into a gay nightclub in Orlando, killing around 50 people and wounding 50 more, according to CNBC. The suspect was later identified as Omar Mateen, aged 29.

The suspect was engaged in a shootout with law enforcement and was killed after a three-hour long spiel. Officials are investigating whether the shooter had ties to any larger organization.

Incidentally, the Facebook Safety Check feature was first included in 2014. Since then, it has acted as a way for users to see the safety status of their friends, family and acquaintances.

Safety Check has been turned on for several natural disasters, accidents and even terrorist attack, the most recent being the Paris attack in 2016.

"Earlier this month, we began testing features that allow people to both initiate and share Safety Check on Facebook," a Facebook spokesperson said in a statement provided to Mashable.

"Over the last few months, we have improved the launch process to make it easier for our team to activate more frequently and faster, while testing ways to empower people to identify and elevate local crises as well."

After deploying the feature on Sunday, the spokesperson said Facebook hopes "the people in the area find the tool a helpful way to let their friends and family know they're okay."