PEKANBARU (JAKARTA POST/ASIA NEWS NETWORK) - The National Police's elite counterterrorism squad Densus 88 apprehended four people in Riau on Tuesday (Oct 24) on suspicions they were planning attacks on police premises in the province.

Two men, who go by the aliases Abu Afif and Abu Ibrohim, were arrested in Pandau Permai residential complex in Kampar regency at around 7.15am on Tuesday.

Based on information provided by the duo, Densus 88 launched another operation later on Tuesday and arrested two other suspected terrorists.

One of the suspects goes by the alias Abu Zahid and was apprehended in Tangkerang area, Pekanbaru city. The other, who goes by the alias Abu Bukhori, was detained in Taman Griya Anggrek residential area in Kampar.

Preliminary investigations by the police indicate that the four men were linked to Jama'ah Anshar Daulah (JAD) and had been making plans to attack the police, including small posts and the Riau Police headquarters in Pekanbaru, said Riau Police spokesman Sr. Comr. Guntur Aryo Tejo.

"Abu Afif is allegedly their leader. There are indications that they are part of a terrorist network (whose members) were recently arrested in Jambi," Guntur said. "The four persons are also suspected to have learned bomb-making in Jambi."

Across the country, police have become the targets of terror attacks by militant groups in the past few years, with the worst attack occurring on May 24 when two suicide bombers linked to the Islamic State in Iraq and Syria group detonated explosives at a bus terminal in Kampung Melayu, East Jakarta, killing three officers.