ISLAMABAD, June 25 (Xinhua) -- At least four people were killed and four others injured in a landmine explosion in Pakistan's northwest Khyber Pakhtunkhwa province on Wednesday, police sources said.

The blast occurred at around 6:20 a.m. local time (0120 GMT) in the tribal district of Kurram when a group of woodcutters accidentally stepped on an improvised explosive device (IED), sources from the district's police told Xinhua.

The injured people have been shifted to a nearby hospital, where two of them are in critical condition.

No group has claimed responsibility for the attack yet, and local officials suspect the IED might have been planted during past sectarian clashes for self-defense purposes.

Local authorities have launched an investigation into the incident. ■