Witnesses said at least one gunman had attacked a cafe in the city centre - near a cluster of embassies - shooting at bystanders, as a series of explosions rocked the area.

Badly mangled bodies were seen lying on the streets as security forces moved in, with regular reports of gunfire and warnings of snipers in the area.

"Four people died, one police officer and three civilians," national police spokesman Anton Charliyan said.

Indonesia, the world's most populous Muslim-majority country, suffered several major bomb attacks by Islamic radicals between 2000 and 2009, including the 2002 bombings on the resort island of Bali that killed 202 people.

A security crackdown weakened the most dangerous extremist networks, leading to a long lull in large-scale strikes.

However, the emergence of Islamic State has raised concern that Indonesians returning from Middle East battlefields could stage attacks on home soil.

As well as the known deaths, a number of people were feared injured in today's assault, with an eyewitness telling that he had seen a 'terrorist' open fire on a local journalist.

The blasts - at least six, according to eyewitnesses – were close to a shopping centre, the Sarinah.

Read more: Three killed in Jakarta blasts

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