Islamabad, Jul 4 (IANS): A health worker of a polio eradication team was critically injured in a firing by unknown gunmen in Pakistan's northwestern Khyber Pakhtunkhwa province, local media reported.

The incident took place on Sunday in the tribal district of North Waziristan where the gunmen fired bullets at the team working on a polio eradication drive to administer polio vaccines in the area, said the report on Sunday.

The attackers fled the spot after policemen escorting the polio workers fired back, Xinhua news agency reported.

The injured person was shifted to hospital, the report added.

It was the second attack on polio workers during the last few days. On Tuesday, three people, including two policemen and a polio worker, were killed in a similar incident in the area.

The anti-polio drive was temporarily suspended in the area following Tuesday's attack, but started again after health workers expressed willingness to continue the door-to-door campaign to inoculate local children aged below five years.