The mass shooting at a gay nightclub in Orlando comes as the Bay Area prepares for huge Pride celebrations, including this month’s San Francisco event that is expected to draw about a million people into the city.

The LGBT community’s pride has grown alongside rising acceptance of same-sex marriage and gay rights. And then, early Sunday morning, a U.S. citizen who reportedly expressed allegiance to the Islamic State trained his sights on gay men and, by association, on the fragile sense of ease that had begun to take hold.

The tragedy deeply affects another community as well. For the second time in less than a year, Muslims face the pain of having to denounce a terrorist attack in the U.S. committed in the name of their faith.

On Sunday night, thousands of people gathered in San Francisco’s Castro district for a vigil and march to City Hall to honor the victims and share their grief. Politicians and LGBT leaders — including San Francisco Supervisor David Campos and state Sen. Mark Leno — spoke out for love, unity and gun control. “We think that because we have same-sex marriage the work is done. It’s not,” said Campos, who was in tears for much of the night. Like many of the Orlando victims, Campos is gay and Latino.

At Harvey Milk Plaza at Market and Castro streets, a huge crowd of mourners waved banners, brightly lit iPhones and candles in plastic cups. The neighborhood’s huge rainbow Pride flag hung at half-staff.

“It’s a chance to be with my community,” said Dirk Nettles, 44. He wore a rainbow flag around his shoulders and kissed friends. “I need to feel like I’m part of something. This is a night of joy and awareness. We aren’t going to let fear rule us.”

Unity in the face of tragedy

In Oakland, Carlos Uribe said he was devastated by the attack apparently targeted at gay people. Uribe, co-chair of Oakland Pride activities, organized a Sunday night Oakland vigil to honor the dead and support those who lost family and friends.

“Please take care of yourself, allow yourself to mourn, to grieve, to be angry, to feel,” he said in a statement.

San Francisco Mayor Ed Lee called the Orlando attack “a stark reminder of the violence that still threatens our LGBT community,” while House Minority Leader Nancy Pelosi, D-San Francisco, vowed, “We will not allow hate and terror to succeed in blinding us with fear.”

Fifty people were killed and at least 53 others were injured in the deadliest mass shooting in U.S. history. It happened around 2 a.m. Sunday when Omar Mateen entered Pulse, a Florida nightclub packed with gay men, and opened fire.

Police arrived and fatally shot Mateen, 29, later identified as an American citizen of Fort Pierce, Fla.

“Let’s be clear: This is an attack on the LGBT community,” said San Francisco Supervisor Scott Wiener, whose district includes the Castro. “There have been way too many attacks on our community. These anti-LGBT hate attacks need to stop.”

Throughout the day Sunday, crowds of people placed flowers, candles and notes at 18th and Castro streets to remember the victims.

Juliette Hirt, 46, who lives in nearby Noe Valley, drew hearts on a red candle at the memorial. She had been walking to a pottery studio when she heard news of the shooting.

“My heart just dropped,” she said. “It was a big shock. I didn’t expect something of this magnitude to happen. There are ignorant, hateful people doing ignorant, hateful things all of the time. And yet it’s still so overwhelming.”

Castro resident Butterfly Guilmette, 23, said it was particularly disturbing to hear that members of the LGBT community were the victims.

“Part of me was like, ‘Oh, it’s another shooting,’ but there was so much pain knowing that queers were targeted,” he said. “There’s a lot of pain right now.”

The FBI is investigating the attack as an act of terrorism. Rep. Adam Schiff, D-Burbank, who sits on the House Intelligence Committee, issued a statement saying law enforcement officials told him the shooting was inspired by the Islamic State group.

Muslims condemn attack

Bay Area Muslim leaders condemned the attack and offered condolences to the families of loved ones killed or wounded in the massacre.

“This cold-blooded killing by a radicalized Muslim has shocked and stunned us beyond words, particularly in the month of Ramadan when we are expected to be especially kind and compassionate,” Hasan Rahim, director of San Jose’s Evergreen Islamic Center, said in a statement.

He said the center “calls upon Muslim Americans to be in the forefront in helping law enforcement officials identify and neutralize such fanatics and killers before they can carry out their deadly attacks.”

In December, Muslim leaders spoke out against attackers who terrorize in the name of Islam after a man and woman carrying assault rifles and handguns killed 14 people at a holiday party in San Bernardino. The shooters, a radicalized Muslim couple, died hours later in a gunbattle with police.

The massacre in Orlando comes as cities around the country hold Pride celebrations, raising fears of more violence. San Francisco Pride events begin next Monday, and the huge annual parade takes place June 26.

The Los Angeles Pride Parade was under way Sunday in West Hollywood, and the colorful celebration briefly became somber as festivalgoers held a moment of silence in tribute to those killed in Florida.

Earlier, Santa Monica police arrested a 20-year-old man, later identified as James Wesley Howell of Indiana, with three assault rifles, high-capacity magazines and a 5-gallon bucket with explosive chemicals, Lt. Saul Rodriguez said. No motive was made clear.

Los Angeles Mayor Eric Garcetti said during a morning news conference that Howell’s arrest was “completely unrelated” to the Orlando attack.

Officials with the San Francisco Pride event said they are working with police to determine what steps to take in the wake of the killings.

“San Francisco Pride and the LGBT community are in mourning for their brothers and sisters and their friends and family in Orlando,” Pride spokesman Sam Singer said. “The most important thing for the 46th annual Pride Parade and Celebration is to show we will not be impacted by cowards or by people who want to terrorize our community and our democracy.”

The San Francisco Pride Parade is one of the largest LGBT events in the world and draws more than 1 million people to the city. The San Francisco Department of Emergency Management will activate its operations center to coordinate with multiple agencies, as it does for all large-scale events.

Officials met Sunday with the San Francisco Police Department and U.S. Department of Homeland Security to look at all potential threats and determine what adjustments should be made, Department of Emergency Management spokesman Francis Zamora said.

‘So incredibly resilient’

Many in the Bay Area’s LGBT community said that they are shocked, horrified and saddened by Sunday’s attack but that the violence is all the more reason to show their pride.

“Even though this incident is the most extreme example of anti-LGBT violence in many years, this is not the first,” Wiener said. “The LGBT community is so incredibly resilient, and we will not let this horrible attack set us back. We will continue to be out and proud.”