ISLAMABAD, Pakistan -- President Asif Ali Zardari's chief security officer was killed in a bombing in the port city of Karachi on Wednesday, raising concerns about the vulnerability of even senior officials to attack by militants.
The attack occurred in the densely populated Gurumandir neighborhood, killing Mr. Zardari's security chief, Bilal Sheikh, and two of Mr. Sheikh's own security guards. Twelve other people, including seven police officers, were wounded, officials said.
Mr. Zardari, who is due to step down as president in September, was not present during the attack, but was in Karachi at that time for meetings, said his spokesman, Farhatullah Babar.
There was no immediate claim of responsibility for the attack on Mr. Sheikh, who was traveling home when his convoy was attacked.
He had stepped out of his armored sport utility vehicle to buy fruit when an explosion ripped through a roadside market. Raja Umar Khitab, a senior Karachi police official, told local news media that the attack appeared to have been carried out by a suicide bomber.
Mr. Zardari's Pakistan Peoples Party portrayed the attack as a warning to the president. "The message is very sinister," Sharmila Faruqi, a member of the provincial assembly, said in a telephone interview Wednesday evening. "If they can get Bilal Sheikh, they can get anyone."
Mr. Sheikh had survived two previous assassination attempts, the most recent in 2011. At the time, he blamed them on political rivals.
Security threats have forced Mr. Zardari to keep a low public profile over his five years as president, limiting his public appearances and leaving him open to charges of being distant from ordinary Pakistanis.
Ms. Faruqi expressed concern over the weakness of Pakistan's security forces, saying that it showed how "ill-informed" the police and intelligence agencies were.
Mr. Zardari's wife, Benazir Bhutto, was killed by militants in 2007. Some supporters were also killed by the Pakistani Taliban in the run-up to the recent elections.
But the party's supporters are also engaged in political violence as part of a bitter turf war for control of Karachi, a commercially important city of 20 million people that is divided between rival political factions.
This article originally appeared in The New York Times.