Photos: World reacts to Orlando attack  Photos: World reacts to Orlando attack  People remember the victims during a vigil at an LGBT community center in San Juan, Puerto Rico, on Tuesday, June 14.  Photos: World reacts to Orlando attack  Jean Dasilva, left, is comforted by Felipe Soto as they mourn the loss of their friend Javier Jorge-Reyes on June 14. They were visiting a makeshift memorial at Pulse, the gay nightclub where the shooting took place.  Photos: World reacts to Orlando attack  Britain's Prince William and his wife, Catherine, sign a book of condolences at the U.S. Embassy in London on June 14.  Photos: World reacts to Orlando attack  A vigil for the Orlando victims is held in New Delhi on June 14.  Photos: World reacts to Orlando attack  Thousands gather in Orlando on Monday, June 13, to pay tribute to those who were killed the day before.  Photos: World reacts to Orlando attack  The Eiffel Tower in Paris is illuminated in rainbow colors on June 13.  Photos: World reacts to Orlando attack  A woman lights a candle during a vigil in Sydney on June 13.  Photos: World reacts to Orlando attack  Runners pass under half-staff flags at the Washington Monument on June 13.  Photos: World reacts to Orlando attack  U.S. Ambassador to Thailand Glyn T. Davies, right, gestures to members of the LGBT community outside the U.S. Embassy in Bangkok, Thailand, on June 13. They were holding a vigil for the victims.  Photos: World reacts to Orlando attack  Students in Mumbai, India, light candles near a rangoli, an Indian form of art created on the ground, on June 13.  Photos: World reacts to Orlando attack  White roses and rainbow flags are displayed in front of the U.S. Embassy in Berlin on June 13.  Photos: World reacts to Orlando attack  People gather for a vigil in Seoul, South Korea, on June 13.  Photos: World reacts to Orlando attack  The city of Melbourne posted this image on its Twitter account June 13 "as a mark of respect for those touched by the attack in Orlando. Town Hall is lit in the rainbow #LoveIsLove."  Photos: World reacts to Orlando attack  Mourners hold an LED sign as they march during a vigil in Dallas on Sunday, June 12.  Photos: World reacts to Orlando attack  Lin-Manuel Miranda, creator of the musical "Hamilton," delivers a sonnet at the Tony Awards to pay tribute to the Orlando victims.  Photos: World reacts to Orlando attack  A rainbow flag flies at half-staff on the Space Needle in Seattle on June 12.  Photos: World reacts to Orlando attack  Henry Duong pays tribute during a memorial service in San Diego.  Photos: World reacts to Orlando attack  One World Trade Center is lit in rainbow colors June 12 in New York.  Photos: World reacts to Orlando attack  Mourners hold up signs during a vigil in Washington on June 12.  Photos: World reacts to Orlando attack  Mourners gather during a vigil in front of the White House on June 12. President Barack Obama called the mass shooting an "act of terror" in remarks to the nation.  Photos: World reacts to Orlando attack  Two women light candles during a vigil in front of the U.S. Embassy in Santiago, Chile, on June 12.  Photos: World reacts to Orlando attack  Mourners observe a moment of silence during a vigil in Atlanta.  Photos: World reacts to Orlando attack  Ryan Gibson, left, embraces Tabor Winstead during a vigil in Raleigh, North Carolina, on June 12.  Photos: World reacts to Orlando attack  A man injured in the attack stands with other mourners as they attend a memorial service at an Orlando church.  Photos: World reacts to Orlando attack  Participants in the Los Angeles gay pride parade show their support for the victims on June 12.  Photos: World reacts to Orlando attack  People hold candles near Rome's Colosseum as they take part in a ceremony on June 12.  Photos: World reacts to Orlando attack  A man places a handprint on a makeshift memorial near the nightclub where the attack took place.  Photos: World reacts to Orlando attack  Photos: World reacts to Orlando attack  People gather in Sao Paulo, Brazil, to mourn the Orlando victims on June 12.  Photos: World reacts to Orlando attack  People gather for a vigil near the Beaubourg art center in Paris on June 12.  Photos: World reacts to Orlando attack  People line up to donate blood at a blood bank in Orlando.  Photos: World reacts to Orlando attack  People show their support for Orlando during the Los Angeles gay pride parade.  Photos: World reacts to Orlando attack  The Rev. Jeffrey Montoya leads a prayer in Greenfield, Wisconsin, on June 12.
When Orange County Sheriff's deputies responded to a call for emergency backup at Pulse nightclub on the night of June 12, they encountered a harrowing scene: