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DALLAS (CBSDFW.COM/AP) — In Dallas, other Texas cities and across the nation, the gay, lesbian and transgender community has seen violence before, from the recent attacks in Oak Lawn to Harvey Milk and Matthew Shepard, and an ever-lengthening list of transgender women. But never anything like this.

Sunday’s massacre at a gay nightclub in Orlando, Florida, grimly changed the equation, stirring communal fears and swiftly prompting tighter security at gay pride events. The gunman, identified as Omar Mateen of Fort Pierce, Florida, told his father he had been disturbed by seeing two men kissing in Miami.

The attack on the Pulse nightclub, which killed at least 50 people and was the deadliest U.S. mass shooting to date, occurred amid numerous events nationwide celebrating LGBT Pride Month. In Dallas and several other cities hosting events on Sunday — including block parties in Boston and a festival in Washington — authorities beefed up the police presence.

This “is a tragic illustration of the legitimate safety fears that those in our LGBT community live with every day,” said Dallas Mayor Mike Rawlings.

Dallas Mayor Mike Rawlings holds a candle during a vigil in Dallas, Texas, on June 12, 2016, for victims of the attack at Orlando's Pulse Nightclub in Orlando, Florida. (credit: Laura Buckman/AFP/Getty Images)

Dallas Mayor Mike Rawlings holds a candle during a vigil in Dallas, Texas, on June 12, 2016, for victims of the attack at Orlando’s Pulse Nightclub in Orlando, Florida. (credit: Laura Buckman/AFP/Getty Images)

As extra police were assigned to the Oak Lawn neighborhood, a hub of the local gay community, Lee Daughtry, owner of Alexandre’s Bar, reflected on the weekend march that had North Texans showing support for those in Orlando. “The overall attitude was a little bit somber. But when we band together what we saw is we can begin to heal our wounds and move forward, and continue the fight for equality, and continue the fight against hate speech.”

Many are hoping that some good — some unity — can come from these tragic events.

A memorial has been growing at the Legacy of Love monument in Oak Lawn. People have been stopping by with flowers, posters, photographs and candles to reflect on the attack, its victims and its impact on the community. The landmark has become the area’s touchstone to what happened in Florida.

Dallas community activist Daniel Scott Cates helped organize the ‘Dallas to Orlando’ vigil for those who lost their lives on June 12. “I think that, for myself and so many in the Dallas community who’ve been impacted by a rash of hate crimes lately, what happened in Orlando hit us in a very personal spot. And I think what you see here at the monument is people who are just heartbroken… absolutely heartbroken,” he said.

The vigil drew thousands of North Texans, from all different backgrounds, to the Resource Center on Cedar Springs Road. The diversity of the crowd was something Cates believes impacted those attending and those who saw the news coverage. “What many in our community learned last night, maybe for the first time and something that some of us have known for a long time, is that we’re not alone. There are so many people out there, who simply because of who they are, because of their skin color, their religion, their sexuality, their gender, are targets of hate and violence. And what we learned last night is those people are ready to link arms together to put an end to this kind of senseless tragedy in our country and we’re ready to join them.”

Organizers also took donations during the Sunday night march, raising $5,600 for the families of the Orlando victims.

In a separate incident Sunday, a heavily armed man was arrested in Southern California even as Mateen’s attack was ongoing, telling police he was going to a gay pride parade. Twenty-year-old James Wesley Howell of Indiana, had assault rifles, ammunition and chemicals that could be used to make an explosive, according to police, who said there was no evidence of a connection to the Orlando massacre. Santa Monica Police Chief Jacqueline Seabrooks initially tweeted that Howell said he wanted to “do harm” at the event, but she corrected her statement to say only that he said he was going there.

“Hug the people that you love. Do it every day,” added Cates. “Because, I think this has really hit home for a lot of us, that life is pretty short. Need to cherish people while they’re here.”

Before Sunday, the most prominent incidents of violence against gays claimed one life at a time. The highest profile of these included the murder of Milk, a pioneering gay politician in San Francisco in 1978, and the 1998 murder of Shepard, a gay college student in Wyoming at the hands of two men who beat him into a coma while he was tied to a fence. A federal hate crimes law bears Shepard’s name.

Investigators were still trying to determine Mateen’s motives. He pledged allegiance to the Islamic State in a 911 call before the shooting, according to according to a law enforcement official familiar with the investigation who was not authorized to discuss the matter publicly and spoke on condition of anonymity.

But LGBT activists had no doubt that their community was the intended target.

“Our practices and institutions may change in light of this tragedy — LGBT gathering places may have more security now,” said Rev. Alisan Rowland, pastor of the LGBT-welcoming Metropolitan Community Church of New Orleans. “But we will never, ever go away. We will never be cowed.”

Rachel B. Tiven, CEO of the LGBT-rights group Lambda Legal, said the continued vilification of LGBT people by their detractors, and the continued resistance to expansion of their civil rights, was “an invitation to violence.”

“When people are targeted by others who are scared of difference, they’re not safe when they go dancing, they’re not safe when they go out to pray,” she said. “If we live in culture where fear of difference is encouraged, that can, in the hands of crazy people, have dreadful consequences.”

There have been a few previous attacks on gay nightclubs, but only one that caused a significant number of deaths. A fire set by an arsonist killed 32 people at the Upstairs Lounge in New Orleans in 1973; the arsonist was never caught.

On December 31, 2013, about 750 people were celebrating New Year’s Eve at Neighbours, a popular gay nightclub in Seattle, when Musab Masmari poured gasoline on a carpeted stairway and set it ablaze. No one was injured, and Masmari was sentenced to 10 years in prison for arson.

Sunday’s attack struck a place that has long been thought of as a safe haven for the community — the gay nightclub.

“Nightclubs have always been sacred spaces for queer people, places to gather and glitter away from the judging glares of society, where we could love and be loved for who we are and how we want to be,” wrote Paul Raushenbush, a clergyman and popular gay writer, expressing his heartbreak in a lengthy, emotional post on Facebook in which he recalled going out dancing while at seminary in New York.

As the owner of Alexandre’s Bar in Dallas for more than 12 years, Daughtry agreed. “Bars have somewhat of a special place to the LGBT community. Before we were accepted in public or accepted by churches this was our meeting place. This was our organizing place. This is a sanctuary for the LGBT community. This is a place where we can all feel safe to congregate and organize.”

“We’ve been talking about it since it happened. It’s so scary,” said Dallas resident Makala Martinez. “It kind of makes us think, well, what’s going to happen here, if anything? Of course, we pray for the families and the victims, and we pray that everyone is held tight in this time.”

In many cities, vigils drew hundreds to commemorate the victims in Orlando. In New York City, LGBT people and their allies converged on the Stonewall Inn in Greenwich Village in spontaneous reaction to the shooting. The Manhattan bar became a national symbol of gay rights after a 1969 police raid led to violent street riots.

(©2016 CBS Local Media, a division of CBS Radio Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)