JAKARTA, Indonesia — Indonesian authorities said Friday they had identified one of the attackers responsible for the deadly explosions in Jakarta a day earlier as a former terrorism convict who was released from prison early.

The disclosure came as police beefed up security in government offices, police stations, shopping centers and diplomatic missions across the capital following Thursday’s attack that left two civilians — an Indonesian and a Canadian — and five assailants dead.

One of the assailants was identified as Afif, who was sentenced to seven years in prison on domestic terrorism charges in 2010. The circumstances of his early release were not disclosed.

Photographs showed Afif, dressed in a baseball cap and jeans, and wearing a backpack and shoulder bag, pointing a gun at a crowd at the scene of the attack on Thamrin Street in Jakarta. Police said the backpack contained explosives and that Afif eventually blew himself up along with another attacker during a shootout with police.

Police spokesman Anton Charliyan said another attacker, whose name was not revealed, was also a former terrorism convict.

Indonesia, the world’s most populous Muslim nation, was the scene of several major militant attacks by al-Qaida-affiliated groups in the 2000s, but Jakarta had not seen a significant attack in several years following a harsh crackdown by police.

Authorities said the Thursday attack was directed and financed by Islamic State, the militant organization based in Iraq and Syria, by an Indonesian living in Syria. The Islamic State claimed responsibility for the blasts in online statements, but analysts said the attack caused significantly less damage than other coordinated attacks attributed to the group, such as the November rampage in Paris that left 130 dead.

Indonesian authorities named the mastermind of the Jakarta attack as Bahrun Naim, who reports said had been living in the Islamic State-held town of Raqqa. Bahrun praised the Paris attacks in a blog post in November and encouraged militants in Indonesia to carry out similar operations.

Jakarta police chief Tito Karnavian said Bahrun had instructed operatives in Indonesia to attack the police and places frequented by Westerners on Christmas and New Year’s Eve.

“We are in the pursuit of other cells and actors,” Karnavian said.

Dozens of Indonesians rallied Friday at the scene of the blasts outside a shopping mall, carrying flowers and shouting, “We are not afraid!”

Police in the city of Balikpapan in East Kalimantan province said they had arrested one suspected militant, but it was not clear if he was related to the Jakarta attack, the Antara news agency reported.

President Joko Widodo said on Twitter that “there is no place for terrorism in Indonesia.”