Interior Minister Mario Fernandez said two police officers were found in the Maule River, adding to the deaths of four firefighters.
A giant Boeing 747 super tanker plane has been loaned from the US to battle the forest fires, Chile's worst in decades.
A state of emergency has been declared south of the capital, Santiago.
Chile's National Forestry Corporation said multiple blazes had affected 238,000 hectares (588,000 acres) and were increasing.
On Wednesday, a firefighter died after getting stuck while trying to help a family escape from their home near the city of Constitucion.
Three others have died and three were injured over the past week. More than 4,000 people have been evacuated from their homes.
The plane can carry 22-times more water and fire-retardants than more common single-engine air tankers.
The cost is being met by the Walton Family Foundation, created by Walmart founders Sam and Helen Walton.
Chilean President Michelle Bachelet also asked for help from French counterpart Francois Hollande, who was visiting Chile.
The authorities also requested planes and helicopters from the US, Canada and Mexico and neighbouring Argentina, Brazil, Uruguay and Peru.
The blazes spread quickly in the dry and particularly hot summer that many South American countries are experiencing.
They have struck mainly in sparsely populated rural areas in the central regions of O'Higgins and El Maule.
Six people have now been killed fighting vast forest fires in central Chile, officials have said.