Amateur video showed moments during the siege that happened in downtown Jakarta on Thursday (January 14).

Just seven people were killed in Thursday's late-morning siege near a busy shopping district, despite multiple blasts and a gunfight, and five of the dead were the attackers themselves.

Nevertheless, it was the first time the radical group ISIS has targeted the country with the world's largest Muslim population, and the brazenness of the attack suggested a new brand of militancy in a country more used to low-level strikes on police.

In the amateur video obtained by Reuters, gunmen were seen shooting at men lying on the ground. The identities of the two men are unknown.

Grenades were also thrown during the standoff.

2016-01-15T132815Z_2_LYNXNPEC0D14L_RTROPTP_4_INDONESIA-BLAST Indonesian police hold rifles while walking behind a car for protection in Jakarta January 14, 2016. REUTERS/Beawiharta Photo: Reuters

Footage also showed gunfights between the police and at least two attackers, who then detonated a bomb.

An Indonesian and a man of dual Canadian-Algerian nationality were killed along with the attackers. Twenty-four people were seriously wounded, including an Austrian, a German and a Dutchman.

Islamic State said in its claim of responsibility that "a group of soldiers of the caliphate in Indonesia targeted a gathering from the crusader alliance that fights the Islamic State in Jakarta."

Police confirmed that Islamic State was responsible and named an Indonesian militant, Bahrun Naim, as the mastermind.

They believe Naim leads a militant network known as Katibah Nusantara and is pulling strings from Raqqa, Islamic State's de facto capital in Syria.

Indonesia has seen attacks by Islamist militants before, but a coordinated assault by a team of suicide bombers and gunmen is unprecedented and has echoes of the siege in Mumbai seven years ago and in Paris last November.