'I heard 20, 40, 50 shots'

Florida shootings - Witnesses to the mass killing at the Pulse nightclub in Florida have described people running and screaming like 'a scene from a horror movie'.

Fifty people are known to have died in the shooting at the gay nightclub, and officials have named Omar Mateen as the suspect, who was killed by police during a shootout.

There were about 320 people inside the club during the shooting, according to the Orlando Sentinel, and Christopher Hanson was one of them.

"It's like you're at a gun range, all you hear is just boom bang bang," he said.

"All you saw is people running and screaming and there were bodies in the parking lot where bodies were being tagged, it was like a scene from a horror movie," Mr Hanson told CNN.

And Jon Alamo said he saw a man holding a weapon walk into the room he was in.

"I heard 20, 40, 50 shots ... The music stopped," he said.

The gunman opened fire in the nightclub at 2am (local time) and shot dozens of people with an AR15 assault rifle and a hand gun, killing 50, and injuring scores of others.

Police said an officer working as a security guard inside the club exchanged fire with the suspect, and a hostage situation developed.

SWAT teams then used armoured cars to storm the club, before engaging in a gun battle and shooting the man dead.

The suspect, who reportedly worked as a security guard and had weapons training, was a self-radicalised lone wolf terrorist.

A trauma surgeon at the Orlando Regional Medical Center, said some of the 53 people wounded in last night's nightclub shooting were in a "dire" condition and the death toll might rise.

The surgeon, Michael Cheatham, said many of the gunshot wounds were severe, with people shot in the trunk, and abdomen.

The hospital called in six trauma surgeons as bloody patients began pouring into its emergency department.

Local residents lined up around the block as blood banks called for donations.

Families waiting

Relatives have been gathering at local hospitals desperate for news of their loved ones.

Many had received calls and texts from loved ones inside the club as the siege began, and some have heard nothing since.

Ten of the victims have so far been named: Edward Sotomayor Jr, Stanley Almodovar III, Luis Omar Ocasio-Capo, Juan Ramon Guerrero, Eric Ivan Ortiz-Rivera, Peter O Gonzalez-Cruz, Luis S Vielma, Kimberly Morris, Eddie Jamoldroy Justice and Darryl Roman Burt II.

Orlando mayor Buddy Dyer asked for patience while the rest were identified and families were notified

Worst ever mass shooting in the US

It is the worst mass shooting in recent US history. Florida governor Rick Scott said it was "clearly an act of terror".

Officials said the killings were likely to be ideologically-motivated, though there was no information that the gunman was associated with a particular group.

However, US Congressman Alan Grayson said it was "no coincidence" the attack happened in a gay club.

"It may be we've seen the commission of an awful hate crime," he added.

Worst US mass shootings in last 25 years:

• At least 50 dead, 2016 - Omar Mateen opens fire on revellers at gay club in Orlando, Florida
• 32 dead, 2007 - Student Seung-Hui Cho massacres students at Virginia Tech university before killing himself
• 27 dead, 2012 - Adam Lanza kills 20 six- and seven-year-old children and six adults before killing himself at Sandy Hook, Connecticut
• 23 dead, 1991 - George Hennard drives through the wall of a cafe in Killeen, Texas, before opening fire and committing suicide
• 14 dead, 2015 - Syed Rizwan Farook and Tashfeen Malik open fire at a staff gathering in San Bernardino
• 13 dead, 2009 - Maj Nidal Malik Hasan opens fire at army base in Fort Hood, Texas
• 13 dead, 2009 - Jiverly Wong shoots people at New York immigrant centre before killing himself
• 13 dead, 1999 - Eric Harris and Dylan Klebold kill fellow students and a teacher at Columbine High School in Littleton, Colorado

The death toll given by Mr Dyer meant that the Orlando attack surpassed the 2007 massacre at Virginia Tech, which left 32 people dead.

"Today we're dealing with something that we never imagined and is unimaginable," he said, adding that there was "an enormous amount of havoc" and "blood everywhere".

"Because of the scale of the crime I've asked the [Florida] governor to declare a state of emergency," he said.

"We're also issuing a state of emergency for the city of Orlando so that we can bring additional resources to bear to deal with the aftermath."

According to the Mass Shooting Tracker, the US last year suffered 372 mass shootings, defined as a single incident that kills or injures four or more people. Some 475 people were killed and 1870 wounded.

Security had also been boosted for the last day of the Capital Pride LGBT festival in Washington DC, which would include a moment of silence for the Orlando victims at 1pm local time.

How it unfolded

Orlando police chief John Mina said the attack began at 2am local time. There was an exchange of fire with the police officer working at the club, but it was unclear whether that was inside or outside the venue.

After this a "hostage situation" unfolded, he said.

Mr Mina said a decision was taken at 5am to send a police assault team into the club after receiving texts and phone calls from some of the hostages.

"Our SWAT officers exchanged gunfire with the suspect, the suspect is dead," he said.

"He appeared to be carrying an assault-type rifle and a handgun, and had some type of device on him."

A bomb squad robot has been searching the scene for possible booby traps.

Mateen's father, Mir Seddique, told NBC News that the incident had nothing to do with religion, but might have been triggered by the sight of a gay couple kissing in Miami.

It was believed that the suspect, who was a US citizen from the Florida town of Port St Lucie and was of Afghan descent, was not on a terrorism watch-list, although he was being investigated for an unrelated criminal act.

The latest incident came as Orlando was still reeling from the fatal shooting on Friday night of 22-year-old singer Christina Grimmie following a concert in the city.

- BBC / RNZ / Reuters