A man shoots into a crowd in Jakarta on Thursday. VERI BAGUS VIA XINHUA

"From what we see today, this group is following the pattern of the Paris attacks."

Witnesses to the carnage on Thursday said a powerful explosion ripped through a branch of US coffee giant Starbucks before at least one gunman emerged and began shooting at bystanders, reloading his weapon as police flooded the streets.

In chaotic scenes, security forces moved in behind the cover of moving vehicles, with regular bursts of gunfire and warnings of a sniper in the area.

The deadly attacks in Jakarta were not a complete surprise to Indonesian authorities, who warned last month of a credible threat.

The government had deployed 150,000 security personnel to safeguard churches, airports and other public places across the predominantly Muslim nation, and it made a series of pre-emptive arrests.