Video report by ITV News Correspondent Lucy Watson
The father of Pc Andrew Harper has said the family are "devastated" following his death.
In the first brief comments from the family, Philip Harper said: "We're absolutely devastated and we're in a bad place."
He spoke as detectives confirmed they have been granted an extra 36 hours to question ten males aged between 13 and 30 over the death of Pc Harper, a newlywed police officer killed after being dragged along by a vehicle in the village of Sulhamstead in Berkshire.
Detective Superintendent Ailsa Kent, of Thames Valley Major Crime Unit, said the 28-year-old died of multiple injuries while responding to a burglary.
Ms Kent told a press conference: "A post-mortem was carried out on Andrew's body yesterday and the cause of death has been recorded as multiple injuries.
"The cause of death is consistent with our current belief that Andrew was caught between a vehicle and the road and then dragged for a distance."
She confirmed that the arrests were made at a council-run caravan and mobile home site, Four Houses Corner, in Reading Road near Burghfield Common.
She added: "The circumstances as to how Andrew came to be out of his vehicle and then caught under the suspect vehicle is unknown."
Ms Kent also urged the public not to speculate on the circumstances of the incident.
On Saturday, forensics officers were seen searching a caravan site on Padworth Road around three miles away from the scene, with two vans appearing to block the entrance.
Later, other officers could be seen gathered around what appeared to be a black hatchback car inside the Four Houses Corner caravan site.
The vehicle, surrounded by police tape and a floodlight, was partially visible through a gap in the fence.
In an update given near the scene, Thames Valley Police spokesman Jack Abell said an emergency call was made reporting a burglary at a residential property at 11.18pm on Thursday.
An officer on duty with Pc Harper was not physically injured but is being provided with emotional support, he added.
Fellow officers have been laying flowers at the scene of the death throughout the morning.
Pc Harper, who has been described by his uncle as the "loveliest person that you will ever meet", married his wife Lissie just four weeks ago.
Photographs of the pair on their wedding day at Ardington House, a Georgian manor in Oxfordshire, have been released.
In one picture the couple can be seen smiling as they cut their wedding cake with a sign next to them reading "happily ever Harper".
Tributes from Pc Harper's family have been left on Facebook with his grandmother, Maureen Shrimpton, writing: "Just a really horrible day.
"Our grandson Andrew was killed last night while doing his police work. So proud of him. Our love goes to his lovely wife, Mum and Dad, brother and all of his family and friends. Love from Nan and Bubba xxx"
His uncle Dale Shrimpton posted: "He's my oldest Nephew. My sister's first born. Mum and dad's first grandson... And was married two weeks ago at a dream wedding. We are devastated.
"He was the loveliest person that you will ever meet. I cant begin to tell you how we feel."
Ms Kent continued: "In respect of our investigation, we are interviewing those in custody, carrying out house-to-house inquiries, obtaining and reviewing CCTV footage, undertaking extensive forensic examination and taking witness statements."
Pc Harper joined as a special constable in 2010 before becoming a police officer a year later, serving in the Roads Policing Proactive Unit based at Abingdon Police Station.