Updated at: 05/28/2013 7:36 PM
By RIAZ KHAN and NAHAL TOOSI
(AP) PESHAWAR, Pakistan - Pakistani authorities suspended a four-day polio vaccination program Tuesday after gunmen shot dead a female polio worker and wounded another, officials said, in a blow to the U.N.-backed campaign aimed at eradicating the crippling disease from this violence-torn country.
Such attacks have made it harder for Pakistan to join the vast majority of nations declared polio-free.
The two women were attacked Tuesday in Kaggawala village on the outskirts of the main northwest city of Peshawar, police officer Mushtaq Khan said.
Senior police official Shafiullah Khan said two attackers on foot fired a pistol at the workers. He said police have started a search operation.
Government official Habibullah Arif said the polio vaccination drive in the northwestern city of Peshawar and nearby villages has been suspended.
The four-day campaign was launched Tuesday morning, but it was halted "for security reasons and to express solidarity with the slain and injured female polio workers," he said.
No group has claimed responsibility for the latest killing, but some Pakistani militants have alleged in the past that the polio workers are U.S. spies and that the vaccine makes people sterile.
Reinforcing those suspicions was the disclosure that the CIA used a Pakistani doctor to run a hepatitis vaccination campaign to try to get blood samples from al-Qaida founder Osama bin Laden’s family before U.S. commandos killed him there in May 2011.
The World Health Organization, the U.N. agency that oversees much of the polio vaccination work in Pakistan, condemned the attack.
Dr. Nima Saeed Abid, acting WHO country head for Pakistan, said the safety of his polio workers, many of whom are women, was paramount.
"I hope the government will provide them with the requested security for the health workers," he said. "And after careful assessment, they should resume their activities."
Pakistani President Asif Ali Zardari blasted what he called a "cowardly" attack, and resolved that "the government will not permit militants to deprive our children of basic health care." He spoke before the decision to suspend the program.
Pakistan is one of only three countries in the world, along with Afghanistan and Nigeria, where polio is still endemic. Health workers have made strides against the disease in recent years, but the violence threatens to reverse that progress.
In December, gunmen killed nine polio workers in different parts of Pakistan. Several more workers have been killed since then, as well as police who were protecting them.
The U.N. said in March that some 240,000 children had missed vaccinations since July in parts of Pakistan’s tribal belt, the main sanctuary for Islamic militants, because of security concerns.
Elsewhere in Pakistan’s northwest on Tuesday, a roadside bomb killed the son of a member of an anti-Taliban militia and wounded the militia member and five others, police official Gul Afzal Afridi said.
The bomb exploded on the outskirts of Mingora, a main town in the Swat Valley, which was once largely under the control of the Taliban until an army operation in 2009.
The militants have since staged occasional bombings and other attacks in Swat. Anti-Taliban militias _ often referred to as peace committees _ have helped hold the militants back.
Afridi said the apparent target Tuesday was militia member Sher Ali. His son Barkat Ali died.
A bomb planted on a motorcycle went off near a place of worship of Shiite Muslims in the northwestern city of Peshawar on Tuesday, killing two and wounding 10 others, police official Zahid Khan said.
Imran Hassan, a resident, said most of the dead and wounded were Shiites.
No one claimed responsibility, but authorities have blamed Sunni militant groups for previous attacks against minority Shiites.
Also Tuesday, gunmen fired on a vehicle carrying a Shiite Muslim lawyer and two of his sons, killing them, in an apparent sectarian attack in Pakistan’s largest city, Karachi, police officer Najam Tareen said.
Karachi, a port city of 18 million, is a hotbed of ethnic, political and sectarian violence, and Shiite professionals are often targeted.
Toosi reported from Islamabad. Associated Press writers Sherin Zada in Mingora, Pakistan, and Atif Raza in Karachi, Pakistan, contributed to this report.
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