pbr Hospital staff say 45 people have been killed and 93 others wounded in a wave of violence which has brought much of Pakistan's commercial capital Karachi to a standstill.br ppbr Dozens of vehicles and shops were set on fire as security forces struggled to gain control.br ppbr Schools and colleges were ordered by the government on Tuesday to close.br ppbr The violence came after Raza Haider was shot dead along with his bodyguard in a mosque in the city while preparing to offer prayers on Monday.br ppbr Local government officials said at least ten people were arrested, and that police and Army Rangers were dispatched throughout the city to impose order.br ppbr The southern city of more than 16 million has a history of political, ethnic and religious violence, and has long been a hide-out for al-Qaida and Taliban militants. Its stability is considered paramount for Pakistan, because it is the country's main commercial hub.