Army trucks thundered through Indonesia's capital Jakarta on Friday as authorities boosted security against possible terror targets and probed the DAESH cell allegedly responsible for deadly militant attacks on Thursday.

Four of the five attackers who died while carrying out suicide bombing and gun assaults on Thursday were identified by police, and a subsequent search of one of their homes found DAESH-related evidence, including the group's flag, National Police spokesman Anton Charliyan said.

On Thursday, a rapid-fire series of bombings and a shootout between gunmen and police erupted in a busy part of the capital lined with malls and foreign missions, shocking Indonesians and leaving two civilians and five attackers dead. Authorities in the world's most populous and democratic Muslim country have blamed a network of DAESH militants from Southeast Asia that was forged in the extremist group's war in Syria and Iraq. "An alert has been imposed throughout Indonesia," Charliyan said. "National police are on their highest alert, especially in areas considered targets of terror, like police stations, government offices, and embassies, with army backup." The spokesman did not elaborate on the army's role, but Agence France-Presse (AFP) reporters saw a convoy of a half-dozen military trucks filled with heavily armed troops in central Jakarta.

Stepped-up police security was also seen at some foreign embassies, and officers in Jakarta and on the resort island of Bali patrolled in riot gear, carrying assault rifles. Indonesia's worst terror incident in seven years left the five attackers dead, as well as a Canadian and an Indonesian man, according to police.

Police have singled out Indonesian extremist Bahrum Naim as being behind the assault. Naim is thought to be in Syria and is said to be a founding member of Katibah Nusantara, a grouping of Southeast Asian fighters there. Terror analysts warn that the group, predominantly militants from Indonesia with others from Malaysia and the southeast Asian region, has threatened for more than a year to bring extremism to Indonesia.

In Indonesia, a country known for its relaxed and moderate Muslim population, as well as other parts of Southeast Asia with Muslim populations, fears have grown that a wave of extremist violence born in Syria could flow back. The attackers included three suicide bombers who initially targeted a Starbucks near a major shopping mall. Men armed with pistols then took two foreigners hostage – an Algerian and a man that Indonesian authorities said was from Canada. The Algerian escaped with bullet wounds, police said, but the second man was shot dead. Two men on a motorbike also destroyed a police post in a suicide bomb attack that left four officers severely injured. Starbucks has closed all outlets in Jakarta until further notice.

Indonesia suffered several large bomb attacks by extremists between 2000 and 2009, but a subsequent security crackdown weakened the most dangerous networks, and there had been no major attacks since 2009.

President Joko Widodo has urged calm, and there seemed little evidence of public jitters, with Jakarta back to its bustling self on Friday, the Islamic holy day. "I am not afraid of terrorists because life is in God's hands, and today is Friday so, God willing, nothing bad will happen," said Toto Suhadi, 52, a gardener watering plants near the attack site.

Large floral tributes to victims marked the scene on Friday. A placard left by one wreath read: "Stupid terrorists! Where did you get the idea that you can go to heaven by killing innocents and then commit suicide, which is banned in Islam?"