Indonesia National Police Chief Tito Karnavian told reporters Monday that officers were working on the assumption that the attacks followed a directive from ISIS central command to avenge the imprisonment of former leaders of Jamaah Ansharut Daulah, an Indonesian jihadi group that supports ISIS.
The group slammed a minivan into a gate and then attacked officers with swords.
The attacks have put Indonesia on edge as the world's biggest Muslim majority country starts the holy fasting month of Ramadan from Thursday. "One of them is being checked by a bomb squad", he was quoted by Kompas TV as saying, referring to a suspected bomb strapped to the militant's body.
Police shot a militant and arrested at least 13 others in a series of raids following the Surabaya attack.
The latest incident comes after an attack on the Surabaya Police headquarters in East Java on Monday morning and three church bombings in the city on Sunday.
Police shot and killed the four suspected terrorists, he added.
The next day, members of another family blew themselves up at a police station in the city, wounding 10.
Islamic State has claimed responsibility for both attacks.
"They were better organized.and suggest a higher level of capacity than what we have seen in recent years", said Sidney Jones, director of Jakarta-based Institute of Policy Analysis for Conflict. A journalist who was at Riau police station at the moment of the incident was also injured as he was hit by a auto, according to Reuters.
Wasisto said the driver has been apprehended and was now being detained at Riau Police Precinct.
Setyo said one of the assailants was captured and taken to the Pekanbaru Police station for interrogation.