Indonesian police said they have arrested 12 people suspected of links to the Jakarta bombings, as the death toll in the brazen attacks by Muslim militants rose to eight after a third civilian succumbed to wounds.

An Indonesian man who was shot in the head when two attackers fired into the crowd died at a hospital late Saturday, Jakarta police spokesman Col. Muhammad Iqbal said Sunday.

The audacious assaults by suicide bombers and gunmen on Thursday targeted a Starbucks and traffic police post in bustling central Jakarta, leaving eight dead, including three civilians, and more than 20 wounded.

It was the first major assault by militants in Indonesia since 2009. Police said the attackers were tied to the Islamic State in Iraq and Syria group (ISIS) through Bahrun Naim, an Indonesian fighting with ISIS in Syria.

National police chief Gen. Badrodin Haiti told reporters the 12 arrests were made in west and east Java and in Kalimantan, the Indonesian part of Borneo Island.

Elaborating on an earlier claim that the militants received funding from Bahrun, he said police have determined money was transferred to Indonesia via Western Union. He said that one of those arrested had received money transferred from ISIS.

Separately, authorities say they have blocked more than a dozen websites expressing support for Thursday's attack as they try to counter radical Islamic ideology online.

Communications Ministry spokesman Ismail Cawidu urged Indonesians to report militant websites and social media accounts.

In recent years, Indonesian counterterrorism forces successfully stamped out the extremist group Jemaah Islamiyah that was responsible for several attacks, including the 2002 bombings of bars in Bali that killed 202 people, as well as two hotel bombings in Jakarta in 2009 that killed seven people.

Jakarta INDONESIA-BLAST Jan 14 2016 target starbucks

A police armoured vehicle is parked outside a Starbucks Cafe near where an explosion went off in Jakarta Thursday. (Achmad Ibrahim/AP)

Terrorism experts say ISIS supporters in Indonesia are drawn from the remnants of Jemaah Islamiyah and other groups, but are also trying to recruit new members.

Police on Saturday also released the names of the eight killed.

Aside from the already-identified Sunakin and Muhammad Ali, the additional attackers were identified as Ahmad Muhazan Saron, who exploded a suicide bomb inside the Starbucks, and Dian Joni Kurniadi. Police said they are still investigating the role of a fifth man known as Sugito. Their ages ranged from 25 to 43.

The civilian victims were Canadian Tahar Amer-Ouali and Jakarta residents Rico Hermawan and Rais Karna.