In a statement released on Wednesday afternoon (early Thursday AEST), Hertfordshire Police said 26-year-old Kyle Clifford had been found in the Enfield area of north London, near his home, and that he was receiving medical treatment for his injuries.
Police did not say how those injuries happened but said they had not fired any shots.
The BBC confirmed that the women killed were the family of its well-known radio racing commentator John Hunt — his 61-year-old wife Carol Hunt and their daughters Louise and Hannah, aged 25 and 28 respectively.
While the manhunt was under way, the public were urged not to approach Clifford.
"Following extensive inquiries, the suspect has been located and nobody else is being sought in connection with the investigation at this time," Detective Inspector Justine Jenkins from the Bedfordshire, Cambridgeshire and Hertfordshire major crime unit said.
"This continues to be an incredibly difficult time for the victims' family and we would ask that their privacy is respected as they come to terms with what has happened."
A colleague of Hunt's and BBC 5 Live's lead presenter Mark Chapman struggled to hold back the tears as he expressed everyone's shock and pain.
"We have a football match to bring you tonight ... and we will start our buildup to it shortly but this has been a heartbreaking day," he said as he opened Wednesday's coverage on 5 Live of England's semifinal match against The Netherlands in soccer's European Championship.
"John Hunt is our colleague and our friend, not just to the current 5 Live sport team but to all of those who've worked here with him over the past 20 years, and also to all of you who have enjoyed his superb commentaries," Chapman said. "So on behalf of everyone connected to 5 Live Sport, our love and thoughts and support are with John and his family."
Jenkins said the investigation was moving "at pace" and that formal identification of the victims was yet to take place.
Jenkins said the investigation is moving "at pace" and that formal identification of the victims was yet to take place. She also said that the "premature" naming of the victims "caused great upset".
Police had been scouring a park in north London, near the home of Clifford, after being alerted about 7pm on Tuesday (4am Wednesday AEST) about the killings in a house in Bushey, a residential area in north-western London.
Police and ambulance crews tried to save them, but they were pronounced dead at the scene.
John Hunt is the main racing commentator for BBC 5 Live, the corporation's main news and sports radio channel. His voice is known to millions through his coverage of the world famous Grand National and The Derby.
The Daily Mail newspaper and others reported that Hunt found the bodies early on Tuesday evening after returning home from reporting at Lingfield Park racecourse south of London.
As part of a note sent to BBC staff, the broadcaster described the incident as "utterly devastating" and that it would provide Hunt "with all the support we can".
Police did not say how or whether Clifford, who is from London, was connected to the women, but British media reported that he was an ex-boyfriend of one of the daughters.
The BBC reported that Clifford left the British Army after a brief period of service in 2022.
Local council member Laurence Brass, who lives nearby, said the area is "a typical leafy British suburb".
"At about eight o'clock last night, I was watching the football on television, and suddenly a helicopter landed in the lawn outside my flat, which is at the top of this road, and then my phone started going, and I was told that there was a major incident here in Bushey and we should all keep away because there was somebody apparently on the run," he told the BBC.
Britain's new home secretary, Yvette Cooper, was kept "fully informed" about the "truly shocking" incident.
People in Britain do not need a licence to own a crossbow, but it is illegal to carry one in public without a reasonable excuse.
A spokesperson for the Home Office said Cooper will "swiftly consider" the findings from a recently launched review into whether further controls on crossbows should be introduced.
