Four pupils are being treated in hospital after a school bus overturned in Northern Ireland.

Police are investigating the circumstances behind the crash, as a mother of one of the child passengers on the double-decker said she heard pupils screaming in fear when her son called her.

The Northern Ireland Ambulance Service (NIAS) said 43 people and a driver were on the vehicle when it crashed in Co Down.

Northern Ireland’s public transport provider Translink has said it is assisting police with their investigation.

The bus had been carrying pupils from Strangford College to Bangor.

Emergency services and a specialist rescue team attended the scene on the Ballyblack Road East near Carrowdore on Monday afternoon.

The double-decker ended on its side in a field.

Two people were rescued from the bus by firefighters using specialist cutting equipment at the scene near Carrowdore.

Strangford College principal Clare Foster said a critical incident response team will assist pupils following the crash.

She said: “This has been a very difficult and distressing experience for the pupils, their families and the wider school community.

“The emergency services were at the scene and we would like to thank everyone who assisted for their quick actions, including a number of staff and parents who provided support and first aid.”

The Northern Ireland Ambulance, which declared a major incident, treated and discharged 33 people at the scene.

Four children were taken to hospital with non-life-threatening injuries and several other patients self-presented at Ulster Hospital.

The PSNI said a casualty centre was set up at Strangford College but added that all children had either returned home or were taken to hospital.

By Monday night, the South Eastern Health Trust said the major incident response had ended but teams continued to treat patients at Ulster Hospital.

Translink chief executive Chris Conway confirmed that an Ulsterbus service carrying school pupils had crashed, adding that no other vehicles were involved.

Dylan Lee, 12, a year eight pupil at Strangford Integrated College, was with his mother Stacey Lee at the scene after the crash.

Dylan told the PA news agency: “I was on the top deck on the right hand side. I was just sitting with my friend: He is fine, he just hurt his arm.

“The bus hit a post and it started to stall and went down this hill.

“It just started shaking. I closed my eyes and then I opened them and I was on the floor.”

He added: “The first thing I did when I got up was to phone my mum.”

His mother said Dylan had a lump and a cut on his head, adding: “I could hear him screaming that he had crashed and I could hear all the kids in the background screaming. It was awful.”

Dylan added: “Then there was this guy came down with a hammer and the windows were all being smashed so we could get out.

“I was crawling under stuff like railings and school bags and stuff. It was on its side in the field.”

The Ballyblack Road is to remain closed while the PSNI investigates.

The Education Authority will work with the school to provide support for any children impacted by the events.

Stormont Health Minister Mike Nesbitt praised the response of emergency service crews and hospital staff.

He said: “This has been a shocking incident and my thoughts this evening are with all of those affected and their families.

“I want to express my heartfelt thanks to the emergency crews attending the scene and to the hospital staff caring for those who have been injured.”

A Facebook post from First Ards Presbyterian Church said it was thinking of everyone involved.

The post continued: “If anyone needs a chat, support, or just someone to listen, don’t hesitate to reach out. We’re here for you.”