Four people were on Wednesday killed in a shootout with police in a village close to the Macedonia-Kosovo border, police said, in the worst incident since the end of the 2001 conflict in Macedonia.

Police said shooting broke out when they tried to stop a van suspected of transporting illegal arms near the village of Radusa.

“We set an ambush and… people from inside the vehicle opened fire, the police responded and four of them (in the van) were killed,” Ivo Kotevski, a spokesman for the Macedonian police, told AFP.

Later on Wednesday Macedonia’s interior minister Gordana Jankulovska told a press conference that the police operation was still ongoing in the sensitive border region which is usually a no-go area for the authorities.

The Radusa hamlet is located in the mountainous border area with Kosovo where most of the villages are inhabited by ethnic Albanians.

Three of the dead were identified as a Kosovo and two Macedonian citizens, said the minister. One was wanted on an international arrest warrant.

Jankulovska added that the authorities had also seized four bags of explosives, anti-infantry mines and other weapons.

The men in the van were dressed in black uniforms and Kosovo Liberation Army (KLA) insignia was found in the vehicle, she added.

The KLA were separatist ethnic Albanian guerrilla fighters that fought against Serb forces during the 1998-99 Kosovo conflict.

The border region between the two former Yugoslav entities is a notorious smuggling route, and authorities in both countries are trying to stamp out the illegal activity.

Last week NATO officials warned that recent incidents of weapons’ smuggling across the border could destabilise the region.

Two weeks ago Macedonia seized weapons including 20 rocket launchers, three mortars, three anti-aircraft guns, 81 kilos (180 pounds) of plastic explosives and hundreds of grenades and mines in the border area.

Unlike most other former Yugoslav republics, Macedonia managed to escape the break-up of Yugoslavia in the 1990s without getting dragged into ethnic conflict.

However in 2001 tensions flared as separatist ethnic Albanian rebels clashed with Macedonian government forces in a conflict that lasted several months.

It ended with a ceasefire deal known as the Ohrid agreement overseen by NATO forces as Macedonian authorities agreed to more rights for the countries 25 percent ethnic Albanian minority.

“There has been a latent crisis in Macedonia since 2001. The Ohrid agreement has never been implemented completely, which creates frustrations on the Albanian side,” said Kosovo political analyst Shkelzen Maliqi.

Macedonia’s Albanians had reverted to radical action to get the attention of the international community for their cause, he added.