An armed group has attacked police stations in central Vietnam, killing four officers. Investigators have detained 26 people.

The Public Security Ministry says the group targeted stations in two villages in the highland province of Dak Lak early on Sunday. It says village officials and residents were also killed or injured.

The group fled after the attack. A search is underway for the members at large.

In Vietnam, the Communist Party exercises absolute rule and anti-government activities are rare. Large-scale attacks on police stations are very unusual.

The ministry has not disclosed the background of the incident or the group's motives.