A elderly man was stabbed to death and a woman in her 60s is fighting for her life after a double knifing.
Dorset Police have launched a murder investigation after the pair were found with stab wounds at an address near Gillingham.
Officers attended the address and found a man aged in his 80s and a woman aged in her 60s, both with serious injuries.
The ambulance service also attended, but the injured man was pronounced dead at the scene at around 9.15pm and the woman was airlifted to Southmead Hospital in Bristol, where she remains in a critical condition.
Their family have been informed and the coroner has been notified of the death.
Following fast-time enquiries by officers, a vehicle believed to be linked to the incident was located travelling eastbound on the A303, Dorset Police said in a statement.
With support from colleagues at Wiltshire Police, Hampshire Constabulary, Thames Valley Police, Surrey Police and the Metropolitan Police, the vehicle was stopped in the Hammersmith area of London.
A 34-year-old man from the Gillingham area was arrested on suspicion of murder and was subsequently taken to hospital for treatment to injuries that are not believed to be life-threatening.
The arrested man and the victims were known to each other, Dorset Police said.
Detective Inspector Simon Huxter, of MCIT, said: “Our thoughts are with the family of the man who sadly died and the injured woman at this extremely difficult time and they are being supported by specially-trained officer.
“We will be carrying out a full investigation to establish exactly what happened at the address in Higher Langham and I would appeal to anyone who saw or heard anything suspicious in the area on the evening of Wednesday 7 April 2021 to please contact us.
“A cordon remains in place at the address and there will continue to be a heavy police presence in the vicinity as we carry out enquiries. Officers can be approached by members of the public with any information or concerns.”