A man and his teenage son from Rotherham were killed when their motorbike was in collision with another motorcycle and a car.
Michael Rowley, 41, and his 14-year-old son Jonathan, who was riding pillion, died in the accident on Friday evening in Gainsborough, Lincolnshire.
Michael, from Clifton, and Jonathan, from Parkgate, were in a group of bikes travelling to Butlins in Skegness.
The police said the driver of the car, a Vauxhall Corsa, had been arrested.
The accident happened on Friday evening by the junction with Thorndyke Way and Corringham Road, in Gainsborough.
'Absolutely shocking'
Michael was pronounced dead at the scene of the crash and his son was taken to Lincoln County Hospital where he died later.
Those travelling on the other motorbike were also injured and taken to hospital.
Inspector Andy McManus said: "There's something about road traffic deaths - I think it's because it is so unexpected, that this is a father and son on their way to a cracking weekend, completely, unexpectedly, gone.
"The trauma of that is phenomenal isn't it? Absolutely shocking."
Police said a Home Office pathologist would carry out a post-mortem examination on Jonathan on Saturday evening.