NEW YORK -- The gay, lesbian and transgender community has seen violence before, from Harvey Milk to 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 Port St. Lucie, 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 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 Mike Rawling, the mayor of Dallas, where extra police were assigned to a neighborhood that is a hub of the local gay community.
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 on his way to attack a gay pride parade.
Twenty-year-old James Wesley, 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.
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.
In Orlando, LGBT groups were banding together at The GLBT Community Center to offer support, including grief counseling, CBS affiliate WKMG reported.
"We're offering a place where anyone can come in to grieve," Lisa Barr, CEO of Hope and Help, told the station. Several organizations sent volunteers to answer calls to a crisis hotline and talk to people in person.
"Anyone who needs help, we're here," Barr said.
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 Dec. 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.
Robert Matencio, who works as a host at Neighbours, said the club responded to the arson attack by adding extra security guards during large special events, and training employees in crowd control.
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.
In many cities, vigils were planned at LGBT community centers and other gathering spots 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.
In front of the red brick façade, Cameron Cano stood proudly with a rainbow flag draped over her shoulders.
"This is where the LGBT rights movement started, and I think the Stonewall represents hope," Cano told CBS New York.
Cano was visiting from Florida, and said the Pulse nightclub is one of the known spots amongst her friends.
"They're always like in the clubs, and this is one of the ones that they always hit up," she said.
Cano said even though society has come a long way since 1969, there are still those who hate the LGBT community.
"What we have to look at is the fact that this was a hate crime, and this was an attack. This was an attack on my community," she said.
Stonewall later held a vigil for the victims outside the bar.
"The LGBT community in NYC stands in solidarity with the communities in Orlando. Our thoughts are with the victims, their families, and those who had to experience such hateful violence," Stonewall Inn said in a Facebook post.
Stonewall is "where we go when things like this happen," said Andy Humm, host of the "Gay USA" TV show.
Many gay bars added security measures, or considered doing so in the aftermath of the Orlando attack.
Boston Police Commissioner Bill Evans said his department has offered help and security to nightclubs in Boston in the wake of the shooting, CBS Boston reported.
"We have a lot of nightclubs that are gay nightclubs," Evans said. "We'll step up our presence, we'll do some outreach today."
Evans said Boston Mayor Marty Walsh reached out to Orlando's mayor to offer assistance.
"The mayor reached out quickly to the mayor of Orlando and obviously offered our prayers, as well as any service we could provide," said Evans. "Both logistically, as well as, heaven forbid, they need additional personnel."
He continued, "I'm sure there's a lot of people hurting down there, and there's a city grieving."
Walsh said in a tweet that a vigil would be held for the Orlando victims at City Hall Plaza at 6 p.m. Monday.
"As a club owner this is our biggest fear," said Jesse Pandolfo, owner of WonderLust, which opened nearly a year ago in Jackson, Mississippi.
She said at least one armed security officer is on duty whenever the club is open; more if she expects a big crowd.
"We are family, and this is really hard for us to handle," she said. "It hits hard, really deeply, and it's scary and it's saddening... We have been pushed around, we have been victimized for a long time."
At eagleBOLT, a gay bar in Minneapolis, patrons watched big-screen TVs in silence as President Barack Obama denounced the Orlando shooting as an "act of terror."
James Parmenter, 28, from West St. Paul, Minnesota, said he comes to gay bars to relax.
"It just hurts me that a place like Pulse was targeted because people go there to feel safe," he said. "You go out, you try to feel safe, and you try to have a good time, and now they seem like targets."