[Omah]

http://www.bbc.co.uk/news/world-us-canada-14509831

Philadelphia's authorities have ordered a weekend evening curfew for under-18 years old in an effort deter teenagers from wreaking havoc in so-called flash mobs.

The phenomenon known as flash mobbing, where groups of teenagers gather after alerting one another via mobile phone, Twitter and Facebook and rampage through the town centre, has frightened residents and alarmed Philadelphia's city government.

While the scenes haven't been as violent or as sustained as those in urban England in recent days, crowds of teenagers have beaten and robbed people and shops have been damaged.

Last Friday 7 August saw yet more trouble in the City of Brotherly Love.

Emily Guendelsberger, a magazine editor, was knocked over by a mob of teenagers in June, just a few blocks away from her home.

Her leg was so badly broken her knee is held together by screws.

"We were going to a friend's house at 21:30 on a Saturday night," Ms Guendelsberger said.

"The front line of the teenagers was yelling at us. Someone grabbed my bag. Someone punched me in the face. I fell over. My friend tried to get me to stand up and it wasn't happening."

Philadelphia Mayor Michael Nutter has vowed to put a stop to the violence, which risks undermining the city's attractiveness to tourists and restaurant-goers.

This is where the US Declaration of Independence was signed and the constitution debated - history which pulls in the visitors.

In a blunt address from the pulpit of his church last Sunday, the African-American mayor told the trouble-making teenagers: "You've damaged yourself; you've damaged another person; you've damaged your peers; and quite frankly you've damaged your race."

From Friday night, police officers can send children found on the city centre streets home once the clock strikes 21:00.

An existing curfew for children has been made even earlier, and parents whose children repeatedly ignore the order could be fined up to $500 (£307).

Philadelphia will keep some recreation centres open until 22:00 at the weekends so that the children barred from the city centre will have something to do.

Will the "mobbing" just spread to the suburbs and satellite towns, though ?