A boy who suffered serious burns during a school Christmas carol event at a south London church is in a critical but stable condition in hospital.

Three people, including the boy, were injured during the incident at Our Lady of the Annunciation church in Croydon at about 2.10pm on Wednesday.

The child, who is understood to be aged between seven and 10, was taken to hospital by air ambulance. A man and a woman were also taken to hospital by road. The boy was attending a carol service with pupils from St Thomas Becket Catholic primary school, which is less than a mile from the church.

Noel Campbell, the headteacher, said: “Our whole school community is devastated by the incident that occurred at our carol service yesterday. Our thoughts and prayers are with the child and his family at this difficult time. Following this incident our pupils, staff and families are being given support.”

Members of the Metropolitan police, London ambulance service and London fire brigade all attended the scene.

A Met spokesman said the boy was still critical but in a stable condition in hospital on Thursday morning.

The Catholic church is part of the Archdiocese of Southwark, which said in a statement on Thursday: “The Archdiocese of Southwark was informed of an incident that occurred at Our Lady of the Annunciation Catholic church in Addiscombe, which led to a child suffering serious burns and two adults also sustaining injuries.

“At this time our thoughts and prayers are with the child and those injured, their families, and the school and parish community. The archdiocese and school involved are cooperating fully with the ongoing investigation.”

The Met said: “Police were called by London ambulance service at 2.21pm on Wednesday 11 December. A young boy was reported to have received serious burns during a Christmas event. The child has been taken to hospital, his next of kin have been informed.”

A spokesman from the London ambulance service previously said: “We dispatched two ambulance crews, an emergency responder, a medic in a car and an incident response officer to the scene. We also dispatched a trauma team from London’s air ambulance.”

The London fire brigade and the Health and Safety Executive were also informed after the incident. An investigation will be opened into the incident by either HSE or Croydon council.