The Skyscraper singer is one of the many stars who have shared both condolences and outrage over the tragedy, which left 49 dead and more than 50 injured after a gunman opened fire at the Pulse hotspot.

On Tuesday (14Jun16), Demi took to Twitter for the first time since the massacre, admitting she has been unable to find the words to express her sadness.

"There are no words for how upset I’ve been since Orlando," Demi wrote. "I cry for the victims, ache for the families, and have immense admiration for the LGBTQ community and their resolve in absorbing this horror and uniting with strength and fearlessness. Stay strong. We stand with you."

She added that more action needs to be taken to prevent a similar incident from happening in the future, writing, "We hurt. We mourn. We argue. We settle. We need to stop the cycle."

Demi has long been a supporter of the LGBTQ community, and was recently feted for her advocacy with the coveted Vanguard Award at the GLAAD Media Awards.

She was presented with the prize, given to media professionals who have made a significant difference in promoting equality and acceptance, by her close friend and touring partner Nick Jonas.

Earlier this year (16), the two decided to cancel a planned concert in North Carolina in protest of the state's anti-gay bathroom bill.

The massacre in Orlando came two days after Demi mourned the loss of pop star Christina Grimmie, who was shot and killed by a fan following an Orlando concert on Friday (10Jun16).

She tweeted, "Praying so hard for Christina Grimmie... What the f**k is wrong with people? #RIPChristina my thoughts and prayers are with her loved ones."