Indonesian police fatally shot four suspected militants Wednesday when they attacked a police headquarters in Riau province.
The attacks have put Indonesia on edge as the world's biggest Muslim majority country starts the holy fasting month of Ramadan from Thursday.
Riau Police Chief Inspector General Nandan said a group of suspected militants crashed a vehicle into the gate of the headquarters around 9 a.m.
The Sunday attacks were followed by another suicide bombing involving a family, this time on a Surabaya police station.
The attack comes days after a series of terrorist strikes in the country, including suicide bombings in three churches on Sunday in Surabaya city, the provincial capital of East Java and a suicide bombing at the police headquarters in the city, which left at least 25 people dead and dozens of others injured.
Media said one attacker may have had a bomb strapped to his body but police did not immediately confirm the reports.
It is said to be the deadliest since the 2002 Bali attack.
Indonesia's security forces have arrested hundreds of militants during a sustained crackdown that smashed some networks, and most recent attacks have been low-level and targeted domestic security forces.
Islamic State has claimed responsibility for both attacks. A suicide bombing was also reported at the city's police headquarters on Monday when bike-borne attackers blew themselves up at the checkpoint to the precinct.
"Four suspects were killed by police personnel during the attack".
Police have been frequent targets of mostly low level attacks by local militants, including a 2017 suicide bombing at a bus station in Jakarta that killed three police officers.