PRISTINA (Reuters) - An attacker threw a hand grenade and fired shots outside a sports hall in northern Kosovo early on Sunday, hours before Serbian Prime Minister Aleksandar Vucic was due to hold an election rally there, police said.

The sports hall is in the small town of Zubin Potok, close to the ethnically-divided city of Mitrovica, a frequent flashpoint between Serbs and ethnic Albanians since Kosovo’s 1998-99 war.

Vucic was touring the area as part of his campaign for the April 24 Serbian general election, in which he is expected to retain power.

Although Kosovo declared independence from Serbia in 2008, Serbs living there can vote in Serbian parliamentary elections.

“A hand grenade exploded outside the sports hall but there are no injuries,” Besim Hoti, a Kosovo police commander in the area, told Reuters.

Hoti said shots were fired at the same place, apparently by the same person who threw the grenade. The attacker had not been identified and there had been no arrests, but Vucic’s visit would go ahead.

Vucic said the attacker had thrown an M-75 hand grenade and fired shots from an automatic rifle in the 3 a.m. (0100) incident.

“He could have killed who knows how many people, because at that time there were 10 people working on setting up the stage,” Vucic told reporters during a visit to the Serbian Orthodox monastery at Banjska.

The Kosovo government has little authority in the volatile north where some 50,000 ethnic Serbs oppose Kosovo’s secession from Serbia eight years ago.

The Pristina government said it had permitted Vucic’s campaign visit. Based on the Kosovo constitution, all Serbs can vote both for the Pristina and Belgrade parliament.

Though Serbia does not recognize Kosovo as sovereign, it signed up to an accord in 2013 designed to settle relations as a condition for Belgrade’s further progress toward European Union membership.

Kosovo declared independence almost a decade after NATO went to war to halt the killing and expulsion of ethnic Albanian civilians by Serbian forces trying to crush an insurgency.