British police launched a murder investigation after an officer was killed in southeast England, the latest in a spate of violent crimes that has forced new Prime Minister Boris Johnson to pledge to do more to protect law and order.

Police said on Friday that constable Andrew Harper was killed while attending a reported burglary late on Thursday near a major road. Ten males aged between 13 and 30 have been arrested on suspicion of murder.

"I am deeply shocked and appalled by the death of a brave officer on duty in Thames Valley last night," Johnson said on Twitter.

Earlier this month the prime minister promised 10,000 extra prison places, 20,000 more police officers and an urgent review of sentencing of criminals.

The focus on crime and other domestic issues before Britain is due to leave the European Union on Oct. 31 has fuelled speculation that Johnson is planning to call an election.

The opposition Labour Party leader Jeremy Corbyn said the officer's death reflected a growth in violent crime in Britain.

"The use of knives, the use of machetes, the use of guns in crime has got to end and it does mean there has to be more police officers available to support people going through these sort of dangers," he told the BBC.