Updated

An EU customs officer in Kosovo was shot to death Thursday in the tense, Serb-dominated north, the EU Rule of Law Mission said.

The incident took place early Thursday during regular staff rotation when two EULEX vehicles came under fire from unknown persons, the Mission said in a statement.

"The incident resulted in the death of one EULEX staff member," it said. "EULEX condemns in the strongest terms possible this act of cowardly violence against its staff members."

The statement did not disclose the name or nationality of the victim. It said a murder investigation is under way.

In Mitrovica, local hospital chief Milan Ivanovic said the victim was shot in the chest and leg, and was dead on arrival.

The EU mission has been overseeing the implementation of the rule of law in Kosovo, former Serbian province which declared independence in 2008, but which remains tense because Serbia and Kosovo Serbs do not recognize the split.

EULEX staff members have been manning check points on the border with Serbia, which has angered hardline Serbs who view the border control as confirmation of Kosovo's independence.

Joint border patrols have been negotiated in EU-brokered talks between Serbia and Kosovo. The former foes signed an agreement normalizing ties in April.