A suspected suicide bomb blast near a polio eradication center in western Pakistan killed at least14 people. Yiming Woo reports.

Video Transcript:

At least 12 of those killed in this explosion were policemen.

They were sent to guard vaccination workers at a polio eradication center in Quetta, near where the bomb went off.

One paramilitary officer and a civilian are also among the dead.

Twenty others were injured.

Police suspect it was a suicide attack.

Teams in Pakistan working to immunize children against polio are often targeted by the Taliban and other militant groups.

They say the campaign is a cover for Western spies, or accuse workers of distributing vaccines designed to sterilize children.

The work to eradicate the virus in Pakistan had some recent success, but violence against vaccination workers has slowed the effort.