Police officers stand guard in front of the family home of a suspected suicide bomber at the Medan City Police Headquarters, North Sumatra, Wednesday, November 13, 2019. Photo: IC

Dozens of suspected Indonesian militants were rounded up after a suicide bomber linked to the Islamic State group killed himself and wounded six others in a police station attack last week, police said Monday.

Some 45 suspects have been arrested since the Wednesday bombing in Medan on Sumatra island, while two bombmakers were shot dead during a raid, according to authorities.

"The pair resisted arrest and tried to attack police with sharp weapons and an air gun," National Police spokesman Dedi Prasetyo told reporters in Jakarta on Monday.

They had built a low-intensity bomb that the 24-year-old attacker strapped around his body, Prasetyo added.

Authorities had earlier said they suspected the bomber was a "lone wolf," following the blast that wounded four police officers and two civilians.

Police stations are frequent targets for radicals in the world's biggest Muslim-majority nation, which has long struggled with Islamist militancy.

About 20 other suspects arrested since the bombing - including the bomber's wife and the couple's religious mentor - played what police described as direct roles in the attack and had links to Jamaah Ansharut Daulah (JAD).

The outfit is a local extremist group that has pledged allegiance to IS and carried out previous attacks, including suicide bombings at several churches last year that killed a dozen congregants.

"The wife together with her husband [the bomber] were members of the JAD network," Prasetyo said.

"They had also attended military camp training ... and were taught how to buy guns and sharp weapons," he added.

The police station attack was revenge for earlier militant arrests by Indonesia's elite anti-terror squad Densus 88, Prasetyo said.

Last month, President Joko Widodo ordered beefed-up security after two JAD-linked militants stabbed his chief security minister, who survived the attack. The Southeast Asian nation of some 260 million has significant numbers of religious minorities - including Christians, Hindus and Buddhists - who have been targeted by radical Islamist groups.