Flags are at half mast at Norfolk Constabulary headquarters in respect of a police officer killed on duty last night.

Ten people have been arrested on suspicion of murder after a police officer was killed while attending a reported burglary in Berkshire.

Prime Minister Boris Johnson said he was "deeply shocked" and "appalled" at the news Pc Andrew Harper had died after a "serious incident" at around 11.30pm on Thursday near the A4, Bath Road, between Reading and Newbury.

Thames Valley Police said 10 boys and men aged between 13 and 30 have been arrested on suspicion of murder and remain in custody at various police stations in the force area.

The incident occurred at the crossroads of Ufton Lane and Lambdens Hill, near to the village of Sulhamstead, police said.

Labour leader Jeremy Corbyn told the PA news agency he was "totally shocked" by the death and said it highlighted the need for more police officers on the streets.

Police said they were still establishing the circumstances in which Pc Harper, from the Roads Policing Proactive Unit based at Abingdon Police Station, was killed while carrying out his duties.

Pc Harper is the first officer to be killed on duty since March 2017, when unarmed Pc Keith Palmer was stabbed by Khalid Masood during the Westminster Bridge terror attack.

The incident comes after a police constable was run over by a suspected car thief in Birmingham last week.

The married 42-year-old traffic officer from West Midlands Police is facing "potentially life-changing" injuries, a senior officer told PA.

A Norfolk Police spokesperson said: "Our thoughts are with PC Harper's family, friends and colleagues at Thames Valley Police following the very sad news of last night's incident.

"As a mark of respect the flags at OCC have been lowered to half-mast."

Andy Fiddler, from Thames Valley Police Federation, said the death of Pc Harper was "totally devastating", adding: "All our thoughts - and the thoughts of the entire police family across the UK - are with the family, friends and close colleagues of Pc Andrew Harper who died last night."

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."

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."