Two off-duty police officers risked their lives to tackle a knifeman who had stabbed one man to death and injured two other people.
The suspect stabbed two men – one fatally – and a woman during an incident in Walton Cardiff, near Tewkesbury, on Tuesday evening.
Gloucestershire Police said two off-duty officers bravely intervened, tackling the knifeman and restraining him.
The force said the Independent Office for Police Conduct has been informed due to previous contact between the suspect and the victim.
Chief Inspector Roddy Gosden said: “The man who was arrested in connection with the incident remains in police custody at this time.
“We can confirm we are not seeking anyone else in connection with our inquiries.
“Our thanks to those who were first at the scene, including two off-duty police officers who bravely intervened to tackle and restrain the suspect.
“Our thoughts at this time are with the family of the man who died and those who were injured.
“Due to previous police contact with the suspect and the victim, the constabulary is referring itself to the Independent Office of Police Conduct. This is a standard practice in such circumstances.
“In light of this, and our ongoing investigation, it would not be appropriate to comment further on the details of the case.”
White forensic tents have been placed over the front doors of two adjacent properties in Snowdonia Road, Walton Cardiff, and part of the street has been cordoned off.
Several uniformed police officers were on duty and forensic examiners could be seen entering and leaving the modern townhouse properties.
Police said the suspect is in his 50s, and the man, aged in his 40s, who was fatally stabbed died at the scene despite receiving medical treatment.
A second man, who is in his 40s, is in a “critical but stable” condition at Southmead Hospital in Bristol, having suffered serious stab wounds.
The female victim, aged in her 30s, suffered a leg injury and was treated at Gloucestershire Royal Hospital.
Mr Gosden added: “This was a horrific incident in a quiet residential area.
“We understand those who saw what happened will be traumatised and many in the local community will be upset and worried.
“Today and over the next few days local policing team officers will be patrolling the area to listen to people’s concerns, refer people to available support and provide reassurance.”
Police also asked anyone who has video of the incident to contact officers and not post it on social media.