On Sunday, one person was killed and eight wounded in shootouts between rival ethnic Albanian groups or in standoffs with police, Interior Ministry spokesman Ivo Kotevski said. Thirteen people were arrested. The State Election Commission suspended voting in at least 17 polling stations due to irregularities or intimidation.
"Even though we have normal voting in most of the country, the incidents in the northwest region overshadowed expectations that we would have the best-organized elections ever and we could prove to Europe that Macedonia has the capacity to conduct a free and fair election," said electoral commission chief Jovan Josifovski.
The violence was concentrated in ethnic Albanian areas. Ethnic Albanians make up a quarter of Macedonia's 2.1 million people. Rebels fought a six-month insurgency in 2001 but since then, a bitter rivalry has intensified among the minority group's political leaders.
Prime Minister Nikola Gruevski's center-right VMRO-DPMNE party is seen as almost certain to win the most votes in the parliamentary election. A recent opinion poll gave his party 31.3 percent compared with the opposition Social Democrats' 11.2 percent.
But it is unclear whether the 37-year-old will be able to win a majority in the 120-seat parliament and avoid having to form a coalition government with another party.
The most serious incidents Sunday were two shootouts with police near the former ethnic Albanian rebel stronghold of Aracinovo and two near the Skopje headquarters of the main ethnic Albanian party in Macedonia, the Democratic Union for Integration.
Kotevski said DUI supporters were firing on police, triggering shootouts.
But Ali Ahmeti, an ex-rebel leader who is now head of the DUI party, accused police of backing criminals he said were targeting his party's supporters.
"What is happening ... is more than slaughtering," Ahmeti said as he voted in his home village of Zajas, 70 miles southwest of Skopje. "We tried to escape provocation, but unfortunately these criminal structures are backed by the police. The situation is quite dramatic."
The head the rival Democratic Party of Albanians, Menduh Thaci, insisted that authorities had the situation under control. "I appeal to the citizens to turn out and vote in big numbers," he said.
Thaci, whose party is part of the outgoing governing coalition, said it was "clear: DUI activists shot at police."
In Aracinovo, near Skoje, Kotevski said police were called in to help election officials prevent a man from voting on behalf of multiple people. DUI supporters fired on the officers when they arrived, Kotevski said. Two people were injured, and one later died at the hospital.
Police conducting a search afterward were involved in a firefight in the outskirts of the village, but nobody was injured, Kotevski said.
Another shootout occurred near the DUI headquarters in Skopje's Cair district. DUI spokeswoman Ermira Mehmeti told The Associated Press that party members had gathered at the building when "all of a sudden, huge shooting started."
Ahmeti - who claims he was the target of an attempted assassination in Tetovo on May 12 - was not in the building at the time.
In a separate incident, gunmen fired at a police vehicle near the DUI headquarters, wounding five people, Kotevski said. And at a nearby polling station, a shootout between supporters of DUI and the rival Democratic Party of Albanians left another two people wounded, he said.
President Branko Crvenkovski appealed for calm.
"I want to express my hope that all this will end, that we will manage to calm the atmosphere and that we will end the day in a way that is suitable for a country with democratic potential," he said.
Voting also was suspended in Gurgurnica near Tetovo in the northwest after men showed up armed with machine guns. Polling stations in Malino, northwest of Skopje, never opened because ballot boxes were stolen overnight, the election commission said.
Voting also was halted in Ciflig in the northwest because of ballot stuffing and in Vrapciste, south of Tetovo, officials said.
Authorities said a record number of police were deployed for the vote. In Tetovo, "no weapons" posters were prominently displayed at the entrance to a polling station.
On the eve of the election, the EU and United States urged the government "to enforce a 'zero tolerance policy' for acts of violence or intimidation.