Hanoi - An exchange of gunfire Monday between two gangs killed six and left several people wounded in the northern port town of Ha Long City, police said.

Vietnamese media reported the killings had occurred at about 5 am (22:00 GMT Sunday) as the gunmen, driving cars and motorbikes, exchanged fire while chasing each other at high speed.

Officer Nguyen The Hung of the Ha Long City police department said police had arrived at the crime scene shortly afterwards and had gathered evidence until noon. He declined to release further details until the investigation is complete.

"We are still investigating the reasons for the killings, so we don't have any basis for saying what caused them," said police detective Tran Huu Tai.

Local media reported the killings stemmed from a turf war between rival gangs.

The Dan Tri newspaper reported a security guard at the city's Long Khanh harbor had heard more than 10 gunshots and found six dead and several wounded people at the scene. The guard said fellow gang members evacuated the wounded before police arrived.

Ha Long City has a high rate of addiction to heroin and other drugs. The region is also the location of numerous illegal coal mines, which have been found in the past to smuggle coal to Chinese ports. (dpa)