Four men who attacked an Indonesian police headquarters with samurai swords were shot dead Wednesday and one officer also died, authorities said, days after a wave of deadly suicide bombings claimed by Islamic State (IS) group rocked the country. The assault in the city of Pekanbaru on Sumatra island – also claimed by IS – saw a group ram their minivan into a gate at the station and then attack officers, police said. Days earlier, two families who belonged to the same religious study group staged suicide bombings at churches and a police station in Surabaya on Java island, Indonesia’s second-biggest city. The attacks have put Indonesia on edge – and sparked a string of foreign government travel advisories – as the world’s biggest Muslim-majority country starts the holy fasting month of Ramadan from Thursday. Four attackers were shot dead at the scene Wednesday and another suspect who fled was later arrested, police said. One officer was killed by the speeding vehicle and two others were wounded in the incident, they added. Police said the men belonged to a local extremist group, but not Jamaah Ansharut Daulah (JAD), which authorities believe was behind the family suicide bombings. Both groups have pledged allegiance to IS, they said. The bloody violence is putting pressure on lawmakers to pass a stalled security law that would give police more power to take pre-emptive action against terror suspects. “I’m outraged and very saddened by these acts carried out by cowards – they have no humanity,” said Pebby Magdalena, who joined a demonstration in Jakarta in support of the bill. Indonesia – which is set to host the Asian Games in just three months and an IMF-World Bank meeting in Bali in October – has long struggled with Islamist militancy. Its worst-ever attack was the 2002 Bali bombings that killed more than 200 people, including locals and foreign tourists. Security forces have arrested hundreds of militants during a sustained crackdown since the Bali bombing. Most attacks in recent years have been limited to low-level operations against domestic security forces. But on Sunday, a family of six – including girls aged nine and 12 – staged suicide bombings at three churches during morning services in Surabaya, killing 13. All six bombers died, including the mother who was Indonesia’s first known female suicide bomber. It was also the first time children had been used in such attacks. A memorial service was held Wednesday for Vincencius Hudojo, 11, and Nathanael Hudojo, 8, two brothers who died after the blast at the Santa Maria Catholic Church on Sunday in Surabaya. Their mother was injured. Services were also held for Martha Djumani, 54, who was killed in the bombing at a Pentecostal church, just a day after she had got engaged. “My sister was always caring towards other people and taught her children to be compassionate,” Daud Samari, Djumani’s younger brother, told reporters. On Monday, members of another family blew themselves up at a police station in Surabaya, wounding 10. The church bombing family were in the same religious study group as the Surabaya police station bombers and a third family believed to be linked to the wave of attacks, authorities said. “They had the same teacher and they regularly met for Koran recital every week,” said East Java police chief Machfud Arifin. The coordinated church attack was a sign local extremist groups are becoming more proficient, and it stirs concerns about an uptick in radicalism as hundreds of Indonesians who flocked to fight alongside IS in the Middle East return home. JAD: the extremist group that recruits families to spread terror in Indonesia “They were better organised … [it] suggests a higher level of capacity than what we have seen in recent years,” said Sidney Jones, director of Jakarta-based Institute of Policy Analysis of Conflict. Dozens of suspects have been rounded up in raids since Sunday’s attacks, while several militants, including the number two ranking leader of the Surabaya JAD chapter, had been shot and killed, police said. The church and earlier police station attacks were likely motivated by the arrest of JAD leaders, authorities said. They followed a deadly prison riot staged by Islamist prisoners at a high-security jail near Jakarta last week.