Police investigate a body part found after suicide bombers struck a Jakarta bus station Wednesday.

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Three police officers have been killed

ISIS has previously attacked Indonesia, the world's most populous Muslim country

Jakarta, Indonesia CNN  — 

A pair of suicide bombers struck a bus station Wednesday in the Indonesian capital of Jakarta, police said.

At least three officers were killed, national police spokesman Setyo Wasisto told reporters. Six other officers and five civilians were wounded.

Aluminium, nails, buckshot and receipts for purchasing rice cookers were found at the scene of the bombing, Inspector General Setyo Wasisto told reporters Thursday afternoon.

It’s not clear who carried out the attack but Indonesian police spokesman senior commissioner Martinus Sitompul said authorities suspect ISIS involvement, according to CNN-affiliate CNN Indonesia.

In the past, ISIS has claimed responsibility for terror attacks in the Southeast Asian nation.

“The Islamic State remains the main driver of attacks in Indonesia, and the threat posed by militants linked to the group is likely to escalate in the country,” Otso Iho, senior analyst at Jane’s Terrorism and Insurgency Center, said in a statement.

“People who have traveled to join the Islamic State in Iraq and Syria (will) begin to return back to their home countries. Experienced returning militants will be able to provide combat training.”

Police bomb squad members inspect the site of the blasts.

The attack came two days before the start of Ramadan. Many of those caught up in the attack had been involved in a torch parade celebrating the start of the Islamic holy month.

Teten Masduki, chief of staff to Indonesian President Joko Widodo, visited the victims of the attack at the Premier hospital on Thursday morning to give his condolences.

“President Widodo condemns this vile attack and asks hospitals to give the best service for the injured,” he said.

Last year, ISIS said it carried out a suicide bombing and shooting near a Starbucks in Jakarta. Two people were killed, and 24 were wounded.

Police said an ISIS militant based in Syria ordered his operatives to carry out that attack.

Indonesia is the world’s most populous Muslim country. In recent years it has been fighting against radical extremism as ISIS attempts to recruit members within the country.

Some Indonesian teachers have instructed students on how to avoid extremist ideology.

Malaysian Prime Minister Najib Razak said Wednesday on his official Twitter that he was “disgusted” by the Jakarta attack.

“Malaysians stand with the Indonesian people at this time. Terrorism has no borders, knows no race or creed,” he said.

Yosef Riadi reported from Jakarta, and Holly Yan reported and wrote from Atlanta. CNN’s Angela Dewan and Ivan Watson contributed to this report.