Three radical person died pursuing a two-vehicle clang connected the Dungannon Road adjacent Cookstown, County Tyrone, Irish broadcaster RTÉ reports.
Four children and a pistillate were besides taken to the Royal Victoria Hospital.
The clang happened soon earlier 15:30 GMT connected Monday.
It is understood 2 radical died astatine the country and a 3rd died successful an ambulance connected the mode to hospital. The roadworthy remains closed betwixt Killycolp Road and Annagh Road.
Police said the closure is apt to stay successful spot for immoderate clip and motorists should debar the area.
The Northern Ireland Ambulance Service (NIAS) said it dispatched 2 accelerated effect paramedics, 4 exigency crews, 1 non-emergency crew, a hazardous country effect squad and an ambulance serviceman to the scene.
The Helicopter Emergency Medical Service (HEMS) Air Ambulance was besides tasked to the scene.
'The worst imaginable news'
Sinn Féin lawman person Michelle O'Neill said it is "deeply tragic news".
"I connection my heartfelt sympathies to the families of those tragically killed and each champion privation to those injured for a afloat and speedy recovery," she added.
Social Democratic and Labour Party (SDLP) MLA Patsy McGlone said it is "the worst imaginable quality immoderate household could person but peculiarly astatine this clip of year".
"My thoughts and prayers are with each those affected astatine this incredibly hard time."
In a tweet, Ulster Unionist Party (UUP) person Doug Beattie said: "I conscionable can't ideate the fearfulness those who survived person endured and the country faced by the exigency services.
"Life is truthful precious and truthful fragile."
Democratic Unionist Party (DUP) person Sir Jeffrey Donaldson said: "Our thoughts and prayers are with each progressive successful this tragic incidental and the families and communities impacted by specified a devastating loss.
"We besides deliberation of the exigency services who attended the country and the wellness work unit caring for those injured."
Elsewhere, the M1 motorway remains closed successful some directions betwixt junction 15 astatine Dungannon and junction 14 astatine Tamnamore pursuing a abstracted crash.
There are nary further details astatine present.