A Taliban suicide bomber detonated his explosives near a vehicle carrying a senior police official in a southern Pakistani port city on Thursday, killing four people, officials said.
Nine people were also wounded in the attack in the Malir area of Karachi, said Manzoor Wasan, the home minister of surrounding Sindh province. The target of the bombing, Malir police chief Rao Anwar, was unharmed, he said. Anwar had been receiving threats from militants.
Javed Ahmad, a police official, said two people died in the explosion and two died of their injuries at a hospital.
Pakistani Taliban spokesman Ahsanullah Ahsan claimed responsibility for the attack in a phone call to The Associated Press.
"We targeted him to take revenge for the torture these officers inflict upon our comrades in custody," said Ahsan.
Karachi is Pakistan's largest city and commercial capital and has a long history of ethnic, sectarian and political violence.
Much of the violence is carried out by gangs allegedly affiliated with the city's main political parties. But the Pakistani Taliban and other Islamist militant groups also have a significant presence in the city.
Associated Press writer Rasool Dawar contributed to this report from Peshawar, Pakistan.