A man is dead and a teenage boy is in a critical condition in hospital after they were stabbed at a Northampton skate park.

Northamptonshire police launched a murder investigation after emergency services were called to the park in Ringway in the Briar Hill area on Wednesday following reports that two people had been stabbed “during an altercation”.

The force said: “Sadly, and despite the best efforts of members of the public and the emergency services, a man in his 20s was pronounced dead at the scene and a teenage boy was taken to hospital with life-threatening injuries. He remains in a critical condition.

“Four people have been arrested in connection with the incident and remain in police custody at this time. Two teenage boys, a man and a woman all from Northampton.”

DCI Torie Harrison, of the East Midlands special operations unit, said: “This is a tragic incident in which a man has sadly lost his life, and a teenage boy is in a critical condition. Our thoughts are firmly with both their families at this difficult time.

“We know incidents of this nature can be a cause of concern within the neighbourhood and wider community, and I would like to offer our reassurance that we have a team of dedicated officers working at pace to establish what has happened.

“High-visibility police patrols will be taking place in the area to reassure the local community, and I would encourage anyone with concerns in the area to approach one of our officers who will be happy to help.

“Arrests were promptly made, and inquiries are continuing to move at a fast pace, however I would still appeal for any witnesses or anyone with information who has not yet come forward to please do so.”

Officers said a police cordon is expected to remain in place at the park as the investigation continues, and several roads are affected by the incident with people urged to avoid the area where possible.

“In addition to house-to-house inquiries, an increased police presence will also remain in the area, including high-visibility patrols to offer reassurance and support the community,” the force said.