India, Aug. 2 -- At least seven people were killed and over a dozen were injured in an explosion during a peace rally in Khyber Pakhtunkhwa province in northwest Pakistan on Sunday.

The blast occurred when the Swat Peace Rally was in progress in Kabal Town in the Swat district, district officials quoted in the PTI report said.

Initial reports indicate that at least seven people have been killed, while 18 are critically wounded, Swat Police said.

"The attacker... detonated his explosive vest, killing seven people, including four police officers, and injuring more than 20 others," Swat's Deputy Inspector General of Police, Fida Hussain, told news agency AFP.

No group immediately claimed responsibility.

Pakistan has previously blamed su...