Jakarta, Indonesia (CNN) -- Police and anti-terror authorities killed three suspects and arrested 15 others in operations in North Sumatra, police said.
Authorities seized TNT and high-powered weapons in the Sunday raids, police spokesman Inspector Gen. Iskandar Hasan said.
But he told reporters that authorities had not yet linked the suspects to terror groups.
Hasan said the weapons and ammunition seized were similar to those used in an August 18 armed bank robbery in Medan, North Sumatra. Police said 16 armed robbers made off with about $44,000 and killed one policeman in the heist.
Terror cells in Indonesia have used armed robberies to raise funds for their operations in the past.