The latest series of violence occurred in the Pureni area, where three people died from gunfire in separate incidents since early last week.
One of the victims was a Grade 8 school student.
Hela province has been plagued by an upswing in bouts of tribal fighting in the past two years.
Fighting spiked again amid mass displacement of people after February's devastating 7.5 magnitude earthquake in the province, leaving dozens of people dead.
However, Hela police said a mediation process which commenced in May paved the way for a truce among several tribes who has been fighting each other.
The heads of police in the province said fighting had largely stopped as a result.