Orlando shooting: How it unfolded in 10 steps

Omar Mateen, who authorities say killed dozens of people inside the Pulse nightclub. Photo / AP

1 Omar Saddiqui Mateen burst into the club at 2.02am local time armed with an AR-15 assault rifle, a handgun, and a device police originally feared was a bomb.

2 He fired off rounds, leaving 39 people dead inside.

3 Emerging, he was confronted by a police officer who was working an extra shift, and exchanged fire. The officer drew the gunman outside on to Orange Avenue.

4 Mateen turned back inside, barricading himself indoors and making those still alive his prisoners.

5 Between five and eight people were in the room with him. A further 25 were trapped indoors.

6 Mateen called emergency services, while inside, to pledge allegiance to Isis (Islamic State).

7 Panicked partygoers had scattered. Some hid in bathrooms. They began to call the police, begging for assistance.

8 About 5am police smashed their way into the building with an armoured Bearcat vehicle. There was an exchange of gunfire with the suspect and he was killed, police said. The Guardian reported the gunman struck one of the officers with a bullet, but the man was saved by his Kevlar helmet

9 Mateen's body had wires attached to it, leading to suspicion he was wearing a suicide vest - something later proved to be false. The officers feared that he had booby-trapped the building, and so robots were sent in to check the area.

10 About 30 people were rescued, the Guardian reported. The death toll climbed to at least 50 and Isis has claimed responsibility.

- UK Daily Telegraph