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nother terror attack against the police despite intensified counterterrorism efforts begs the question: To what lengths will the terror group go to carry out itsmission?

In the latest in a string of terrorist attacks in East Java, the Riau Police headquarters in Pekanbaru was attacked by five men on Wednesday morning.

After crashing through the main gate in a white Toyota Avanza, four of the attackers, wielding samurai swords, attacked and wounded Comr. Faridz and Brig. Jon Hendrik. The attackers, identified as Mursalim, 42, Suwardi, 28, Adi Sufiyan, 26, and Daud, were shot dead by police officers.

The as-yet-unidentified fifth attacker, who was driving the car, crashed into several people in an attempt to flee the scene, killing traffic police officer Second Insp. Auzar and injuring two reporters.

The driver was later arrested and is being detained at the Pekanbaru precinct office.

“Based on our findings, this group is part of the Islamic State of Indonesia [NII] that is affiliated with ISIS in Dumai,” National Police spokesperson Insp. Gen. Setyo Wasisto said on Wednesday.

The Riau attack comes days after a series of deadly blasts in Surabaya and Sidoarjo, East Java, which police say were carried out by the pro-Islamic State (IS) group Jamaah Ansharut Daulah (JAD).

Presidential Chief of Staff Moeldoko called the attacks a reaction to counterterrorism efforts. “[The attacks are happening] because the police are pressing them, triggering a reaction,” he said on Wednesday. “The important thing is that the police cannot let up in their efforts.”

East Java Police chief Insp. Gen. Machfud Arifin said the terrorist networks in Surabaya were “sleeper cells” that were reactivated for numerous reasons, one of which was the rearrest of JAD ideologue Aman Abdurrahman for his alleged involvement in the 2016 attacks in Central Jakarta.

Institute for Defense Security and Peace Studies executive director Mufti Makarim agreed, saying he thought the rapid rate of attacks indicated a speeding up of the terrorists’ plans. “If we look at the pattern, it’s clear there was a certain amount of planning involved, but we have to look at the surrounding events to get a clearer picture.”

Mufti noted that the arrests of suspected terrorists prior to the National Police’s Mobile Brigade headquarters (Mako Brimob) riot, followed by the riot itself, might have prompted pro-IS militants to move their plans forward or change their targets for fear of detection.

“For example, the attacks in Surabaya were on houses of worship, when typically these groups target police officers, such as in the attack in Riau,” he said.

Despite belonging to different groups, Setyo said the attackers in both regions were part of the larger pro-IS network in Indonesia. “They all pledged allegiance to [IS leader] Abu Bakr al-Baghdadi.”

The counterterrorism squad Densus 88 has intensified its crackdown on pro-IS cells across the country since the East Java attacks. The police have shot dead four and arrested 13 alleged terrorists in the province since Sunday, most recently capturing alleged East Java JAD leader Abu Umar in Malang.

The East Java Police are also hunting two radical preachers who allegedly gave sermons at a regular religious gathering attended by the families involved in Sunday’s bombings.

Densus 88 and the North Sumatra Police have also conducted several raids in Medan and surrounding areas on Tuesday, killing at least one.

“We cannot reveal the number [of people arrested], because the situation is still developing,” North Sumatra Police spokesperson Adj. Comr. Tatan Dirsan Atmaja said on Wednesday.

In Tangerang, Banten, Densus 88 and the Tangerang Police raided three locations in the Pinang district on Wednesday, arresting three alleged terrorists.

Setyo said the three men — identified as MC, G, and A — were alleged members of JAD’s Jakarta wing. When asked whether the recent attacks were connected to last week’s riot at Mako Brimob, he would only say that the Riau attackers were connected to terror detainee Benny Syamsu Tresno, who was killed by police during the riot.

An Indonesian IS newsletter, confirmed by a police source and seen by The Jakarta Post, calls on IS supporters to “kill infidels wherever they are” and displays a photograph of Benny’s body, calling him a “martyr”.

Marguerite Afra Sapiie in Jakarta and Apriadi Gunawan in Medan contributed to the story