QUETTA - Unidentified gunmen killed four health workers, including three women, taking part in an anti-polio campaign in Quetta on Wednesday, highlighting the challenge the country faces in stopping the spread of virus. The killings took place around 10 am on the outskirts of Quetta, according to police officials.

The vaccination campaign in Quetta district was halted immediately after the attack, but officials said it would continue in other districts of the province. “Three females and one man died in the attack,” Noor Baksh Mengal, the police official in charge of the neighborhood where the killings took place, said by telephone. “Three other female workers are also wounded.”

The wounded workers were admitted to a hospital, and their condition was said to be not life-threatening. Mengal said that two attackers riding a motorbike had opened fire on a van carrying the health workers. He said the workers were not accompanied by a police security team at the time, and he faulted them for not properly coordinating with the police. He said the workers were to meet a police team and were on their way to that meeting when they came under attack.

However, provincial Home Secretary Akbar Durrani told AFP, “A team of seven polio workers was getting ready to launch the fourth and final day of the campaign when two men riding a motorbike opened fire on their vehicle,”.

A senior doctor at Quetta’s Civil Hospital, Rasheed Jamali said a male and a female health worker died on their way to hospital while two female workers died of their wounds in hospital.

The vaccination team leader, who wished to be identified by her first name ‘Rubi’, said the driver of her minivan fled when the men on the motorbike pulled out in front and flashed a gun.

“Then they started firing from the front, I received bullets and fell down, I was bleeding. Then they went to the side of the vehicle and started firing,” she said.

Rubi and others got out of the minivan after the gunmen fled the scene - but minutes passed before they could flag down help.

“I was bleeding and feeling so weak but I struggled to get down and saw a policeman nearby. I screamed for help but he walked away and disappeared down a street,” she said. “I kept on screaming, begging for help but vehicles wouldn’t stop.”

A motorcycle rider finally came to their aid. But two more workers, a husband and wife, died of their injuries on their way to hospital.

Haleem Shah, president of the Polio Workers Association of Balochistan, said his colleagues would not go back to work until they were assured of greater security.

“The government provides security for one day and if nothing bad happens then they take the security back,” he said.

“We are in contact with the government and we have demanded that we won’t participate in the campaign until we are provided security.”

District health officer Sher Muhammad said the campaign was launched in eight districts of Balochistan including Quetta three days ago.

“It was the last day of the campaign to administer drops to the remaining children,” he said, adding that the campaign was stopped in Quetta after the attack.

There was no immediate claim of responsibility for the attack, but Taliban militants have repeatedly targeted health workers across the country in a fight against polio immunization. The militants accuse the health workers of being spies and agents of the West.

The attack was later condemned by federal Information Minister Pervez Rashid, who said militants would not succeed in their “nefarious designs”.

In a statement, the minister reiterated the government’s resolve to make Pakistan a polio-free country. He added that the elements targeting the anti-polio teams were enemies of the state as they were trying to damage the image of Pakistan at international level.

Pervaiz resolved that they would not succeed in their nefarious designs. He expressed heartfelt condolences with the families of the deceased and prayed to the Allah Almighty to rest the departed souls in eternal peace. He also prayed for early recovery of the injured.

In most cases, however, health workers remain vulnerable to militant attacks even with a security detail. Health workers have been repeatedly targeted in Khyber-Pakhtunkhwa Province and in Karachi.

Pakistan is one of only three countries where polio remains endemic and attempts to stamp it out have been badly hit by opposition from militants and attacks on immunization teams, which have claimed more than 60 lives in the last two years.

Pakistan has reported 246 cases of polio so far this year, compared with 74 in 2013, according to official statistics. Quetta is considered a high-risk area for the spread of the virus.

Among the new cases detected, 136 are in the troubled northwestern tribal areas that border Afghanistan and are the stronghold of Taliban and Al-Qaeda militants.

Opposition to immunisation increased after the US Central Intelligence Agency orchestrated a fake vaccination campaign to help catch Al-Qaeda chief Osama Bin Laden.

The outbreak led the World Health Organization earlier this year to ask Pakistan to impose mandatory vaccinations on travellers leaving the country.

An international monitoring body also blamed Pakistan’s government in a report last month. Vaccinators rarely get paid their government stipends, while police protection teams often turn up late, if at all.

The complacency of Pakistan’s government was “disastrous”, the report said, warning that the country risked reinfecting the rest of the world. Pakistan has already exported the virus to Syria, China, Israel and Egypt.