Britain mops up after 4th night of mayhem (VIDEO)

Cleaning crews mopped up after a fourth night of urban unrest in major British cities and towns as Prime Minister David Cameron recalled Parliament to address the reasons behind the U.K.'s worst riots in 30 years.

According to the Wall Street Journal:

Many of those who witnessed the near lawlessness on London's streets Monday night described the unrest as a straightforward criminal spree by opportunistic youths greedy for consumer goods. Mr. Cameron, returning to London on Tuesday after breaking off his summer vacation in Italy, condemned what he called "pure criminality."

Others blamed deep-seated frustration at high unemployment, cuts to public services and bad policing for rioting and looting in London neighborhoods as well as in Birmingham, Liverpool and Bristol that police called the worst civil violence in living memory.

Overnight Wednesday, the trouble that started in the North London suburb of Tottenham over the weekend and peaked Monday night, had spread to Greater Manchester, Liverpool, Nottingham and Birmingham, with shops there being looted and set alight.

(GlobalPost reports: U.K. riots spread to Manchester)

The scene in London, where 16,000 police were deployed, remained relatively quiet, the BBC reports.

A total of 768 arrests has been made in connection with violence, disorder and looting in London, Scotland Yard said, the Guardian reports.

In Birmingham, police launched a murder inquiry after three pedestrians — possibly brothers and protecting their neighborhood — were run over. Two were killed and a third reportedly was in a critical condition at Birmingham's City Hospital.

In Greater Manchester overnight, fire bombs were thrown at shops and looters stole mainly clothes, electrical items and alcohol.

Assistant chief constable Garry Shewan told the BBC:

"This has been senseless violence and senseless criminality of a scale I have never experienced in my career before.

The violence began after last week's fatal shooting by police of Mark Duggan in Tottenham, an ethnically mixed North London neighborhood. Family and friends of the victim staged a peaceful protest outside a Birmingham police station that turned violent and morphed into a general lawlessness in London.

(GlobalPost reports: Why London exploded last night) 

According to the AP:

While the rioters have run off with goods every teen wants — new sneakers, bikes, electronics and leather goods — they also have torched stores apparently just for the fun of seeing something burn. They were left virtually unchallenged in several neighborhoods, and when police did arrive they often were able to flee quickly and regroup.

Cameron, meantime, vowed to stay in the capital as long as necessary and was due to chair a meeting of the Cabinet's emergency committee Cobra for the second day running.

Cameron recalled parliament from its summer recess for an emergency debate on the riots Thursday.