A man has been arrested on suspicion of causing death by dangerous driving after a crash in which six people, including four members of the same family, were killed.
Nine-year-old Rubie Morgan-Roller and Lillie Morgan-Roller, four, were killed alongside their mother Shannen Morgan and father Shane Roller when the car they were in collided with a motorbike.
Christopher and Janine Barton, who were both travelling on the motorcycle, also died in the crash on the A61 between Barnsley and Wakefield on Sunday afternoon.
Police have appealed for anyone who saw a grey Porsche 911 being driven in the area around the time of the collision to come forward.
West Yorkshire Police said the man was arrested earlier and remained in custody.
They also urged anyone who may have dashcam, CCTV or doorbell footage of the car and the manner it was being driven to contact them.
Det Sgt Steven Suggitt said: “I would like to appeal for anyone who may have seen this grey Porsche 911 being driven on the roads around the south of Wakefield or north of Barnsley to please contact us.”
The Bartons’ BMW S100 XR motorbike and the family’s Ford Focus collided on the road at about 15:55 BST.
Mr Roller and his partner had another daughter, aged 11, who is understood not to have been with them at the time of the crash.
Paying tribute in a post on social media, Mr Roller’s father said his son and daughter-in-law “thought the world of their little family”.
He said: “On Sunday we lost part of our family, Shane Roller, Shannen Morgan and two beautiful little granddaughters in a terrible car accident.
“Shane wasn’t just a son but an amazing father and he had a heart of gold .
“Shannen, our daughter-in-law, was funny and was also an amazing mum and they thought the world of their little family.
Mr Barton, 56, and Mrs Barton, 48, had recently celebrated their 25th wedding anniversary.
In a tribute issued by West Yorkshire Police, their son described the couple, who lived in Barnsley, as “a loving, caring mum and dad who always put me before everything else”.
Clare Storr and Kirsty Wordsworth, co-head teachers of Athersley North Primary School, which Rubie and Lillie attended, said the girls were “a delight to teach”.
“The girls were a credit to their parents, who were always incredibly supportive and who will also be greatly missed,” they said.
More than £340,000 has been raised for the surviving daughter of Mr Roller and his partner after a GoFundMe campaign was set up by family friend Paul Hepple.
Mr Hepple said the youngster had “lost her whole world in an instant” and the donations would “ensure she has a stable, loving environment where she can heal and grow”.
A special service was held earlier at St Helen’s Church in Athersley to allow people to pay their respects to those who died.