A hotel owner has been arrested on suspicion of manslaughter after three teenagers died outside a St Patrick's Day disco, his spokeswoman said.
Michael McElhatton, 52, owns the Greenvale Hotel in Cookstown in Co Tyrone.
It is understood the other suspect, 40, is a member of the popular nightspot's door staff.
The suspects are in police custody.
The youngsters died after a crush at the premises on Sunday evening which eyewitnesses described as chaotic.
AMENDMENT: Detectives from PSNI Major Investigation Team investigating the deaths of three teenagers at the Greenvale Hotel in Cookstown on Saint Patrick's Day have arrested two men aged 52 and 40 earlier today on suspicion of manslaughter. They are currently in custody.
— PSNI (@PoliceServiceNI) March 19, 2019
Hundreds of mourners have left written and floral tributes to the three teenagers who died.
Students Lauren Bullock, 17, Connor Currie, 16, and Morgan Barnard, 17, all from nearby Dungannon in Co Tyrone, perished.
Up to 400 people were present as the tragedy unfolded, and detectives said it was fortunate more were not killed.
Police confirmed some were trampled underfoot as they waited to enter the disco.
A Police Service of Northern Ireland (PSNI) statement on Tuesday evening said: "Detectives from PSNI major investigation team investigating the deaths of three teenagers at the Greenvale Hotel in Cookstown on Saint Patrick's Day have arrested two men aged 52 and 40 earlier today, Tuesday 19 March, on suspicion of manslaughter.
"They are currently in custody."
On Tuesday, tearful well-wishers embraced tightly after laying flowers at a shrine to the dead beside a police cordon.
Books of condolence across the county filled with page upon page of tribute.
Eyewitness Eboney Johnston, 16, recalled: "People just started to fall, but as one person fell another went down.
"As a person went to lift another person up, they were pushing and shoving and another person would fall, which caused a build up of everybody lying there."
PSNI Detective Chief Superintendent Raymond Murray said: "This is an event that should have been a celebration and it has turned into every parent's worst nightmare."
He added: "Bad enough, a horrendous tragedy, but we could easily have been looking at more."
Buses let youngsters off outside before the disaster happened.
Ms Johnston described the unfolding events.
She said: "We looked down and you could just see everybody lying there and then you could just see Connor himself being took out.
"It was just such a tragic situation."
Youngsters will not face police action for being under age if they come forward, prosecutors pledged, in a bid to encourage people to tell their stories to officers.
Mr Murray praised those in the crowd who worked hard to get party-goers who had fallen down back on their feet when others were tumbling on top of them.
Lauren was a bright and bubbly cheerleader and schoolgirl who lit up the lives of her friends, a close friend said.
Alice Lambert, also 17, from Coalisland in Co Tyrone, was among the first to sign the memorial book in Cookstown.
She said: "She was such a nice person – she was like a ray of sunshine.
"She made you happy, you saw her on a night out and she would have made you happy."
St Patrick's Academy in Dungannon, where the two other victims attended school, said it was a time of "profound sadness".
Morgan was an "ambitious and charismatic" young person with abundant potential.
Teachers said: "He lifted the mood everywhere he went, everyone benefited from Morgan's energetic, positive zest for life. It was contagious.
"His smile was bright and when Morgan was around, fun and laughter always followed."
Connor was a kind-hearted, loyal friend, always willing to help others, "courteous, mannerly and compassionate".
The school said: "He had a great sense of team spirit and his warm, caring nature endeared him to all and earned him much deserved respect."
Counselling services are being provided to those affected and prayer services have been held.
Northern Ireland Secretary Karen Bradley signed the Cookstown book of condolence and met members of the emergency services.