A Pakistani plain-clothes policeman fire

A Pakistani plain-clothes policeman fires a tear gas shell towards demonstrators during a protest against alleged target killings in Karachi on May 20, 2010. At least 17 people including two children have been killed in political clashes in Pakistan's financial capital Karachi in the past two days, a government official and police said. Police and paramilitary have been put on high alert and authorities closed all schools and colleges after the latest outbreak of politically related violence in Karachi, the biggest and richest city in Pakistan. AFP PHOTO/RIZWAN TABASSUM (Photo credit should read RIZWAN TABASSUM/AFP via Getty Images)