Two women in the team survived the attack, CNN reported. More than 500 teams were doing a door-to-door vaccination push in the Swabi district in Khyber Pakhtunkhwa province in northern Pakistan, Faazil Khan, a police official, said.
Last month, eight health workers were killed in a series of attacks on vaccination teams.
Dr. Mohammad Riaz, who is in charge of the campaign, said teams would continue their work Wednesday, the final day.
Pakistan is one of three countries where polio remains endemic, along with neighboring Afghanistan and Nigeria. The government has stepped up efforts to vaccinate the population with the number of reported cases dropping sharply last year to 58 from 173 in 2011.
But the Pakistani Taliban, who control much of the northwest, said in June that no children should be vaccinated until the United States halts drone strikes. Pakistanis have also become more suspicious of vaccination because the CIA faked a vaccination drive in 2011 to get DNA samples from residents of the Abbottabad compound where Osama bin Laden was believed to be living.