Jakarta attacks

Photos of a mystery pistol-brandishing copper, who appeared straight off a Hollywood set, sent netizens' hearts aflutter with his slicked back hair, sunglasses and flashy sneakers.

A police source said the three men were arrested at 4am this morning from a house in Cimanggis, Depok.

"They were sleeping when we arrived there," the police officer said. 

He said police seized two bags and some books but they were not analysed right away as it was still dark.

At least six people have been killed by the blasts, which hit several locations including a shopping centre.

Police say they believe more than a dozen attackers were involved. Some are still at large and have been exchanging fire with security forces.

President Joko Widodo has called for calm but condemned the "act of terror".