Security forces in Karachi have been ordered to shoot on sight to stem violence in which 80 people have been killed since Tuesday.
The violence is widely blamed on armed gangs from rival political parties.
The BBC reports Pakistan's biggest city is virtually shut down. Many shops, schools and offices are closed and there is hardly any traffic on the streets.
Most people are staying at home fearing more trouble. The government says it has deployed an extra 1000 troops.
Interior Minister Rehman Malik said that most of those who had died were innocent people.
He added that 89 people had been arrested for involvement in the violence.
