The Police Service of Northern Ireland (PSNI) said there were a “small number” of other casualties following the incident. Two people were being treated in hospital. One was in a critical condition and the other was stable police said.
“Family members of all four people have been informed,” the force said. “Our thoughts are with everyone involved. The police investigation is continuing.”
Police had urged parents via Twitter to pick up children attending a St Patrick’s Day event the venue had been hosting.
Emma Heatherington, whose two sons, aged 17 and 18, had been at the event, said she “felt sick” when she saw the police appeal.
“My two boys were there so I rang them, shaking and thankfully got them both,” she said.
“They were on their way home at that stage. They say there was a huge crowd waiting to get into the venue and then a lot of commotion up near the front of the queue, then they said the emergency services arrived and they were all asked to leave.
“They came home very, very shaken with rumours that some people had died.”
The force’s assistant chief constable, Mark Hamilton, said: “While the exact cause of the incident is still unknown, there are reports of a crush at the scene. At this stage, the cause of the incident is unknown. However, police have commenced a full investigation into the circumstances.”
The incident at the Greenvale Hotel on Drum Road happened at about 9.30pm. The Northern Ireland ambulance service (NIAS) said they had received several calls on Sunday evening following reports of people having sustained serious injuries.
The ambulance service said: “NIAS despatched two rapid response paramedics, two doctors and five emergency crews to the scene. Three patients have been taken, by ambulance, to Antrim Area hospital for treatment for various injuries and another to Craigavon Area hospital.”
Colin Neill, the chief executive of Hospitality Ulster, said: “We are devastated to hear of the confirmed PSNI report of at least two deaths this evening at the Greenvale Hotel in Cookstown. This is shocking and tragic news and our thoughts and prayers are with the families of the deceased.”
The Democratic Unionist party leader, Arlene Foster, tweeted that her “thoughts and prayers” were “with everyone impacted by this tonight”.
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