Dozens killed in Karachi poll violence

Gunmen have killed at least 25 people in Karachi in the past 24 hours, raising tensions in Pakistan's largest city as voters cast ballots to replace a provincial MP murdered in August.

Police said they were still investigating the motives behind the shootings, but many so-called "target killings" in Karachi have been linked to gangs controlled by the city's main political parties, which have been feuding for much of the past 20 years.

"We cannot say whether all the killings were politically motivated or some gangs were involved because the killings took place in different parts of the city and were not confined to the area where the elections were being held," police chief Fayyaz Leghari said.