Nightclub floor covered in blood after massacre
Isil claims attack that killed 50 clubbers, injured 53 more
The initial round of gunfire was lost amid the colourful lights and thumping music at Pulse nightclub in Orlando, Florida.
Lost, that is, until victims began to fall to the ground and the screams began. When the music cut out, the hundreds of people inside the gay club realised they were under attack. Those that could do so fled, but scores remained trapped inside.
Omar Saddiqui Mateen burst into the club at 2.02am armed with an AR-15 assault rifle, a handgun and a device police originally feared was a bomb.
His Afghan-born father said Mateen had expressed anger at seeing two men kissing. The FBI were aware of him, but had not opened an investigation - he was still working as a security guard, allowed to carry concealed weapons, and charged with protecting federal buildings. Police said Mateen "had weapons training".
He fired off round after round while shouting out in a foreign language, leaving 39 people dead inside the club.
Emerging, he was met by a police officer working an extra shift at the club and exchanged fire. Mateen turned back, barricading himself inside and making those still alive his prisoners.
Between five and eight people were in the room with him. A further 25 were trapped inside the building.
Mateen (29) reportedly called 911 from inside to pledge allegiance to Isil. He also reportedly mentioned the Boston marathon bombers.
Panicked partygoers began to call the police, begging for assistance.
"Right after 5am we made a decision to go in," said John Mina, chief of Orlando police. He said they smashed their way into the building with an armoured vehicle.
"We were being contacted by hostages. So we used a BearCat to go in. There was an exchange of gunfire with the suspect and he was dead at the scene."
Inside the room, the floors were covered in blood. Mateen's body had wires attached to it, leading to a suspicion he was wearing a suicide vest - which later proved to be false.
Officers also feared he had booby-trapped the building, so robots were sent in first to check the area.
Once police could enter the rest of the building they found the devastation was worse than imagined. The death toll climbed swiftly from 20 to at least 50, with 53 more rushed to nearby hospitals, some critically wounded.
The city was still reeling from the murder the previous night of Christina Grimmie, a 22-year-old singer from 'The Voice', who was shot dead outside a concert venue by a deranged gunman.
Christopher Hansen was inside Pulse when the shooting began. "I don't think anyone really knew what was going on until they saw people on the ground bleeding and heard people screaming," he said. "I crouched low and ran."
Mr Hansen said he removed a bandana from the head of one victim and used it to try to plug his wound.
Luis Burbano was about to leave when the shooting began. He said 20 or 30 people darted into the same small alleyway as they scrambled to get away. He feared he would be trapped but a hole had already been kicked into a fence by the panicked crowd.
Authorities put out appeals for blood and a state of emergency was declared.
US president Barack Obama called the shooting an "act of terror" and an "act of hate".
It is thought there were more than 300 people inside the building at the time of the attack, which has now become the worst mass shooting in American history.
At a press conference Mr Obama said that as Americans they are "united in grief, in outrage and resolve to defend our people". "The FBI is appropriately investigating this as an act of terrorism, and I directed that we must spare no effort to determine what, if any, inspiration or association this killer may have had with terrorist groups," he added.
Isil's claim was carried by Amaq, the terrorist group's news agency.
"The armed attack that targeted a gay night club in the city of Orlando in American state of Florida which left over 100 people dead or injured was carried out by an Islamic State fighter," said the Amaq statement.
The FBI cautioned, however, that proving the suspected link to radical Islamism required further investigation.
Two US officials familiar with the investigation into the massacre said that no evidence had yet been found showing a direct link between the massacre and Isil or any other militant group.
The officials, who spoke on condition of anonymity, also said they had yet to see any direct contacts between any extremist group and the suspect.
US Representative Adam Schiff of California, the senior Democrat on the House Intelligence Committee, said several factors indicated the attack was an Isil-inspired "act of terrorism". Mr Schiff noted that the incident occurred during the Islamic holy month of Ramadan, that Isil had called for attacks during that period, the target was an LGBT nightclub and it was hit during Gay Pride weekend.
"Ramadan, the month of conquest and jihad. Get prepared, be ready... to make it a month of calamity everywhere for the non-believers..." said the statement allegedly made by Abu Muhammad al-Adnani over Twitter. "The smallest action you do in their heartland is better and more enduring to us than what you would [do] if you were with us."