London, which is to stage next year's Olympic Games, witnessed a third night of violence Monday as other cities saw unrest. Protesters were seen destroying and looting shops, setting cars and buildings alight and engaging in clashes with police.
The riots took in their grip cities like Birmingham -- where the England and Indian cricket teams were holed up in a hotel ahead of their Test match scheduled to begin Wednesday, Liverpool, Nottingham and Bristol and Manchester.
Violence began in the British capital's northern district of Tottenham Saturday over the fatal shooting of a man by police.
Some 300 people gathered outside a police station in Tottenham Saturday night to demand "justice" after 29-year-old cab driver and alleged drug dealer Mark Duggan was killed in Thursday's shootout with police.
Cameron, who cut short his holiday following the rioting, said that rioters will "feel the full force of the law".
The prime minister said the parliament was being recalled Thursday due to the violence that has spread to other cities in Britain.
The government's emergency committee Cobra has met over the deadly riots, reported BBC.
"We will do everything necessary to restore order to Britain's streets and make them safe for the law-abiding," said Cameron.
The prime minister said that at least 450 people have been arrested so far.
He warned rioters, "you will feel the full force of the law", and added that people should "stand together in condemnation of these crimes".
Britons are shocked by the scale of violence.
Christian Potts, a resident of Ealing, said: "It looks like a war zone - I have never seen anything like it in all my life."
"There were about 25 to 30 masked youths and they just started tearing into a florist with bricks," BBC quoted him as saying.
The Sun reported that children as young as eight were spotted throwing bottles at police officers.
It said that the trouble-makers used social networking to organise the violence and destruction across the capital.
Home Secretary Theresa May said: "These have been the worst scenes of violence and disturbance on our streets for many, many years, and this sort of violence, this level of criminality, this thuggery, this looting, this theft, is completely unacceptable."
"We can deal with it. We can deal with it with robust policing, with good use of intelligence, but also with the help and support of local communities."
Authorities said that an extra 1,700 officers had been deployed across the capital Monday night.
London continued to witness violence stretching the emergency services beyond limit on a third night of rioting in the capital, the Guardian said.
Buildings were set ablaze, shops looted, and police officers attacked as gangs of hooded youths roamed the streets.
A police station in Holyhead Road in Handsworth, Birmingham, was on fire and 100 people were arrested.
There were reports of cars being damaged in Britain's Manchester city and of up to 200 youths with masks roaming through Toxteth in Liverpool city.
Police in Bristol said they were dealing with outbreaks of disorder involving about 150 people.
A senior police official pledged that those responsible "will face the consequences of their actions and be arrested".