PRISTINA, Kosovo (AP) — Kosovo authorities on Friday condemned a recent string of armed attacks against police in which automatic rifles and hand grenades were used as acts of terrorism.

Interior Minister Xhelal Svecla said the latest attack occurred early Friday when a police patrol came under fire from an AK-47 assault rifle and a hand grenade near Zubin Potok, 55 kilometers (35 miles) north of the capital Pristina. Three other attacks against police occurred in the previous two days.

Svecla said that none of these attacks intended to frighten or eliminate police officers succeeded in their aim.

Police Chief Samedin Mehmeti said two police vehicles were damaged but their bulletproof windshields protected the occupants.

Mehmeti added that the previous evening, 30 rounds were fired from inside Serbian territory at a police patrol near a path used by smugglers.

Svecla accused Serbia of trying to destabilize Kosovo.

Kosovo declared independence from Serbia in 2008, a move recognized by the United States and most EU nations. Serbia has refused to recognize Kosovo as separate nation after 11 years of EU-brokered negotiations.

The U.S. Embassy said it was “deeply concerned” by recent reports of gun fire directed at police and strongly condemned “this deplorable, unjustifiable violence.” It also cautioned against speculation that would increase tensions.