A murder investigation has been launched after a police officer was killed as he attended a reported burglary.
Thames Valley Police said Pc Andrew Harper died following a "serious incident" at around 11.30pm on Thursday near to the A4, Bath Road, between Reading and Newbury.
Ten males aged between 13 and 30 have been arrested on suspicion of murder and remain in custody at various police stations across the Thames Valley , a statement from the force said.
The incident happened at the crossroads of Ufton Lane and Lambdens Hill, near to the village of Sulhamstead, Berkshire police said.
PC Harper, from the Roads Policing Proactive Unit based at Abingdon Police Station, was killed while performing his duties, the force said in a statement.
Deputy Chief Constable Jason Hogg said: "Our deepest thoughts at this time are of course with Andrew's friends and family, who are being supported by specially trained family liaison officers.
"Our thoughts also extend to all of Andrew's colleagues within Thames Valley Police.
"As a force we are devastated at the loss of our colleague and will all be supporting each other at this difficult time."
Officers remain at the scene of the incident. Ufton Lane and Lambdens Hill remain closed but the A4, Bath Road, has reopened, police said.
Senior investigating officer Detective Chief Inspector Stuart Blaik, of the Thames Valley Police Major Crime Unit, said: "This is a tragic incident, and I would like to reassure the public as well as our officers and staff that we have launched a full and thorough investigation to establish what has happened.
"We have made a total of 10 arrests in connection with this incident, and those arrested are currently in police custody. Those arrested are all male and aged between 13 and 30.
"I would appeal to anyone who witnessed this incident to get in touch. If you have any information which you think could be at all relevant to our investigation, no matter how insignificant it may seem, please leave details on our website or call 101."
Prime Minister Boris Johnson has said he is "deeply shocked and appalled" by the death of "brave" Thames Valley police officer Andrew Harper after he was killed as he attended a reported burglary in Berkshire.
He said: "I am deeply shocked and appalled by the death of a brave officer on duty in Thames Valley last night.
"My thoughts are with Pc Harper's family, friends and colleagues at this terrible time.
"It is the most powerful reminder that police officers up and down the country put themselves at risk every single day to keep us safe.
"They have my absolute support."
Labour leader Jeremy Corbyn said he was "totally shocked" by the death of PC Andrew Harper, and said it highlighted the need for more police officers on the streets.
Speaking from Machynlleth during a visit to Wales on Friday, he said: "I'm totally shocked at Andrew Harper's death, and my immediate thoughts are condolences to his family and to his colleagues who must be going through some awful moments at the present time.
"He was doing his duty apparently investigating a robbery of some sort, and was killed in the line of duty.
"Ten people have been arrested already, which I hope is good news in the sense that they are taken out of the equation and can't commit any more crimes if they are indeed the guilty ones.
"Let's just think for a moment of the horror of it, but also for the need for more police officers to be able to respond to disorder in our society, but also the problem of guns and the problem of violence that is growing."
