By Press Association and Q Radio News
Books of condolence are to be opened in memory of three teenagers who died following reports of a crush outside a St Patrick's Day disco.
Cheerleader Lauren Bullock, 17, keen sportsman Connor Currie, 16, and Morgan Barnard, 17, from Dungannon in Co Tyrone, died in the tragedy at the Greenvale Hotel.
Police said it appeared that people had fallen and then been fatally injured, but are still investigating the cause.
The books of condolence will be opened on Tuesday morning at The Burnavon arts centre in Cookstown, at Ranfurly House, Dungannon, and at The Bridewell centre in Magherafelt.
Councillor Sean McPeake, chairman of Mid Ulster District Council, said there had been an "outpouring of grief" in the local community, and that the books would help people express their sympathies with the victims' families.
The incident unfolded at around 9.30pm on Sunday as several hundred people tried to get into the venue in Cookstown.
One teenager who witnessed a crush outside the disco said it was the most frightening moment of her life.
"As I looked down I could see multiple bodies underneath me and as I looked up I could see multiple bodies on top of me," she said.
"It was the most traumatic, frightening and stressful moment of my life."
Emergency services attended within minutes and attempted to resuscitate the victims.
Two were taken to hospital critically ill but died later. One died at the scene.
Northern Ireland Ambulance Service's medical director Dr Nigel Ruddell said: "Everything points towards it being a tragic accident."
People struggled to get off the ground and there was confusion, the Police Service of Northern Ireland (PSNI) said.
Assistant Chief Constable Mark Hamilton said: "It is a truly awful incident, heart-wrenching for everybody, particularly the families.
"Everybody did their best for them last night but it is a truly appalling incident.
"Unfortunately three are dead. The last person died this morning, unfortunately, with his parents near him."
Mr Hamilton said preliminary investigations showed there was a crush towards the front door of the hotel, and in that crush people seem to have fallen.
Security camera footage is being examined and police have appealed for videos captured by those present.
Lauren was a "beautiful soul" who was the backbone of her cheerleading team, a social media post said.
Her cheerleading team added: "My heart is broken writing this. You were the most down to earth, beautiful soul and our Coral team will never be the same without you."
She was a pupil at St Patrick's College in Dungannon. Principal Catherine McHugh described her as a "shining light".
"She was a leader among her peers and a quiet, strong and loyal presence. A treasured friend and capable young lady with a bright future."
Edendork Gaelic Athletic Association football club said it was devastated to hear of the death of "much loved and highly thought of" player and member Connor.
It said: "Connor will forever be remembered with the greatest affection by all associated with our club and indeed the wider Edendork community."
A relative of Morgan said he was a keen football player.
He added: "He was just a bundle of joy, always bouncing around, he seemed to have a lot of energy in him - a gentleman, he was.
"I am gutted. I just could not take it in, I tried to sleep and I could not sleep."
The hotel can take up to 500 people and attracts people from across the country.
Owner Michael McElhatton gave CPR to the victims.
He was clearly emotional as he spoke to media yesterday afternoon:
A 16-year-old girl is in a stable condition in hospital, while another two teenagers were treated for injuries.