Updated

At least nine health care workers in Pakistan have been murdered this week by militants who oppose the country’s polio vaccination program, which has now been suspended in the areas of the attacks.

The killing began in Karachi on Monday, when a supervisor of a polio vaccination team was killed. Four vaccine administrators, all women, were killed on Tuesday. On Wednesday, gunmen shot dead a female health worker and her driver in the town.

The killings continued, with two more deaths, even after Pakistani officials in the affected areas announced the program’s suspension. All but one of the health workers killed were contracted by the Ministry of Health in Pakistan.

A police investigator told Fox News the attacks “were well coordinated in the time frame the assailants executed them,” suggesting the attackers were from a single group.

“Most of the polio workers were shot at point blank,” a Pakistani Intelligence officer said. “This is (a) typical style of Taliban.”

But while the Pakistani Taliban has accepted responsibility for similar attacks in the past, reports said the group denied carrying out the most recent killings.

Militants suspect people working for the United Nations or non-governmental organizations that manage the vaccine programs are actually spies for the United States. Others mistakenly believe or spread the false claim that the polio vaccine will make children sterile.

Militants targeted the polio campaign last year after unverified reports surfaced that Dr. Shakil Afridi had helped the CIA run a fake polio campaign in the northwestern city of Abbottabad to gather DNA from the Bin Laden compound. The campaign was in fact for Hepatitis B, but militants still view the anti-polio vaccine as American poison.

The call to suspend the program was made by Pakistani and not by U.N. officials, said Peter Smerdon, an official with the U.N. Children’s Fund, or UNICEF. “That decision has to be taken by the government and, unfortunately, they’ve had to temporarily suspend their polio activities as we have had to ours,” he said.

The polio campaign in Pakistan is spearheaded by the government and supported by UNICEF and the World Health Organization.

A U.N. press release condemned the killings, saying they are “not just attacks on highly devoted health workers and volunteers, but on the health of Pakistan’s children. The provision of basic health services, including vaccination, is a fundamental human right, and to deny this access through violence and intimidation is unacceptable.”

Pakistan ranks second among the three countries where the polio threat still exists, ahead of Afghanistan and behind Nigeria. Efforts to eradicate polio in Pakistan have thus far proven beneficial, officials said, reducing the number of cases by 70 percent.

Pakistan Interior Minister Rehman Malik declined to comment to Fox News on Pakistan’s security measures taken in the wake of the attacks.

Since 2009, at least 19 aid workers have been murdered and 23 kidnapped in Pakistan, excluding the recent killings, according to Pakistan Humanitarian Forum.

Pakistan has yet to arrest suspects in the case of a British aid worker killed in April, or to secure the release of Warren Weinstein, an American aid worker for J.E. Austin kidnapped last year in the eastern city of Lahore.