Jakarta, Indonesia (CNN) -- Unknown gunmen fatally shot three policemen Wednesday at a police station in Indonesia's North Sumatra province, authorities said.
Men on motorcycles entered the police compound about 1 a.m. and shot the officers, who were on duty at the district police station in Deli Serdang, said District Police Chief Inspector General Oegroseno. Oegroseno, who goes by one name, spoke on local television.
The killings raised speculation about a link to recent police raids and the arrests of suspected terrorists in North Sumatra.
No such link had been established, police spokesman Marwoto Soeto said.
On Sunday, Indonesian authorities killed three suspects and arrested 15 others in raids. Ties were later established between the 18 and terrorist groups, police said Monday.
The raids netted TNT and high-powered weapons, police said.
The three suspects who were killed Sunday, and three of those arrested, were involved in a bank heist in August, National Police Chief Bambang Hendarsono Danuri said at a news conference Monday in Medan, North Sumatra. The men belonged to a terror cell in charge of raising money to buy weapons, the chief added.
The suspects were part of a militant training camp in Aceh, which authorities raided earlier this year, and fled to nearby Medan to raise more money, Danuri said. Police are still hunting for other members of the group.
Terror cells in Indonesia have used armed robberies to raise money for their operations in the past.