The LBGT community in Florida and across the United States is reeling from the mass shooting that left at least 50 people dead in on Sunday.

The attack began at around 2am on Sunday morning when gunman Omar Siddique Mateen opened fire inside Pulse, a popular dance spot in downtown Orlando that was hosting Latin night. After a hostage situation and an hours-long standoff, Mateen was killed in a shootout with police shortly before 6 am.

Mateen's father, Mir Siddique, told NBC News that the incident "had nothing to do with religion," but said he recalled his son becoming enraged after he witnessed two men kissing in downtown Miami several months ago.

"We were in Downtown Miami, Bayside, people were playing music. And he saw two men kissing each other in front of his wife and kid and he got very angry," Siddique said. "They were kissing each other and touching each other and he said, 'Look at that. In front of my son they are doing that.' And then we were in the men's bathroom and men were kissing each other."

Pulse is jointly owned by Ron Legler and Barbara Poma, who reportedly opened the business partly as a tribute to her brother, who died from HIV/AIDS. The name Pulse was for her brother's heartbeat, which Poma said she wanted to keep alive with the creation of the club. On its website, the club describes itself as "a place of fun and fantasy."

Beau Adams, 28, used to work as a host at the door, and his boyfriend worked as the club's barback. Adams wasn't at Pulse last night, but he goes there often. He woke up on Sunday morning to text messages and missed calls from worried friends. Adams said that Orlando is a tight-knit community for gay and straight people alike, and that he and his boyfriend are waiting anxiously for authorities to release the names of victims.

The average night at Pulse is "diverse, straight, gay, all kinds of races, all kinds of styles," Adams said. "You walk in the door and see happy faces. It's just so hard to believe."

"Ever since I woke up this morning all I could hear is helicopters," Adams said. "You can't believe it. This is Orlando. You never think it's going to be us. But today it was."

There will be a community vigil at 7pm on Sunday in downtown Orlando. Adams plans to attend, and hopes that the community can "come together and be stronger."

Vigils in solidarity with the 50 victims are being planned across the country, including at the Stonewall Inn, the legendary gay bar in New York City.

President Barack Obama said that the attack was "an act of terror" and "an act of hate."

"This is an especially heartbreaking day for the LGBT community," Obama said, adding that an attack on sexual orientation or gender is an "attack on all of us."

The attack came at a time when the country is celebrating its annual LGBT Pride month, which has been observed since the 1970s after the Stonewall Riots in New York.

Before Sunday, the deadliest attack on LGBT community was in 1973 at a bar in New Orleans that also hosted church services. In that incident, a fireball burst through the club's front door, killing 32 people. No one was ever prosecuted.

The Harvey Milk Foundation, a gay rights advocacy group named after one of the first openly gay elected officials in the US, put out a statement that said the victims in Orlando "had their futures stolen, had their dreams stolen, had their potential contributions stolen from us all."

"Hate and separation continue to bring forth too much grief, too many stolen lives across the world," the statement said. "May we also have the strength to address and deal with the roots of hatred that target any minority community with violence anywhere in the world."

My heart aches to release such a sad statement. Orlando LGBT community and leaders being held in our prayers! — Stuart Milk (@StuartMilk)June 12, 2016

Other LGBT advocates and celebrities have been expressing their support and sympathies through social media.

I am sickened to awake to the horrific news out of — Ross Mathews (@helloross)June 12, 2016

I am gay and I am not afraid. Love conquers all. — Ricky Martin (@ricky_martin)June 12, 2016

Sobbing. — Ellen DeGeneres (@TheEllenShow)June 12, 2016

Deeply moved that in the face of tragedy Orlando & Americans everywhere are coming together to give blood, love & support.This is who we are — Laverne Cox (@Lavernecox)June 12, 2016