Parts of Pakistan's largest city Karachi have been shut down after a wave of violence that has killed at least 60 people since Saturday. Security forces are patrolling the city to prevent fresh violence.

Some shops were set on fire in an outlying neighborhood of Karachi, where police tried to calm gathered crowds. Police detained 55 suspects in connection with the latest violence, and say that some were linked to local political parties. The killings in Pakistan began ahead of a by-election to replace a provincial lawmaker murdered in August.

The two parties, which are said to be most linked to the violence- the Muttahida Quami Movement and the Awami National Party - have electoral bases in different ethnic groups that make up a large share of the city's population. Both parties are competing for Haider's seat, but the Awami boycotted the poll, saying its opponents would rig the vote. The Muttahida Quami Movement won the seat.