Four women and three men suspected of being sorcerers allegedly responsible for the death of a woman leader were rounded up, bound with ropes and slashed with sharp objects.
The incident occurred on Tuesday night at a settlement on the fringe of Lae, following the death of one of the community's leaders.
Lae City acting metropolitan superintendent Leo Lamei has confirmed mobile squad police had attended to reports of the attack.
Those involved in the alleged attack eluded the police but returned after they left and continued their torture of the seven people, witnessed by many of the settlement's residents.
According to eyewitnesses, the attackers used sharp knives to slash and stab at the faces and bodies of the seven, leaving them seriously injured.
According to the reports, the attackers are Chimbu men and relatives of the dead leader.
The seven vcitims, said to be from the same clan, have not reported to police.
It is said that the ritual is customary in Chimbu province, where people suspected of being sorcerers, are rounded up and tortured until they admit to the charges.