A biker is in critical condition in hospital following a two-motorbike crash on Wareham Road in Holton Heath.
The incident happened on Sunday evening just before 7pm near to the Blackhill Roundabout, where the road was closed till 3am.
It involved a grey Honda motorbike and a red Honda motorbike.
Emergency services attended the scene and the rider of the grey Honda, a man aged in his 40s, was taken by air ambulance to Southampton General Hospital, where he remains in a critical condition. His family has been informed.
Following enquiries, a 55-year-old man from Poole has been arrested on suspicion of driving offences.
Police Sergeant Richard Stroud, of the Roads Policing Team, said: “We are carrying out extensive enquiries into the circumstances of this collision and our thoughts are with the seriously injured man and his loved ones at this time.
“I would urge any witnesses or motorists with relevant dashcam, as well as anyone with information that might assist our enquiries, to please contact us.
“Finally, I would like to thank members of the public for their patience and understanding during the road closures.”
Anyone with information is asked to contact Dorset Police at www.dorset.police.uk, via email at scit@dorset.pnn.police.uk or by calling 101, quoting occurrence number 55250063173. Alternatively, independent charity Crimestoppers can be contacted anonymously online at Crimestoppers-uk.org or by calling Freephone 0800 555 111.