Four police officers, two local officials and three civilians died in the rare shootings that occurred in the early hours of Sunday in Cu Kuin district of Vietnam's Central Highlands.

During a speech to garment workers, Prime Minister Hun Sen characterised the shootings in Vietnam as a "terrorist attack" and speculated that those responsible might be hiding in Cambodia.

He ordered armed forces in the northeastern region to "check villages thoroughly" along the border with Vietnam.

"I am concerned that these people are hiding among the villagers," Hun Sen said, adding that authorities must arrest and hand them over to Vietnam if apprehended.

Vietnamese authorities arrested at least 46 people in connection with the shootings, police said Friday.

Police were searching for more suspects.

Gun violence is uncommon in Vietnam, where it is illegal for citizens to own firearms and the black market for weapons is limited.

The Central Highlands, home to several ethnic minority groups, is considered a sensitive area for Vietnam's authoritarian government and has long been a hotbed of discontent over issues that include land rights.

Some tribes in the area -- collectively known as Montagnards -- sided with the US-backed south during Vietnam's decades-long war. Some are calling for more autonomy, while others abroad advocate independence for the region.

Scores of Montagnards in past years fled into Cambodia to escape discrimination in Vietnam and sought asylum at the United Nations refugee agency in Phnom Penh.

Hun Sen on Friday warned the UN refugee agency and international organisations to be on the lookout for the suspects and not offer them help.

He said Cambodian authorities had been cooperating with Vietnam since the attack.