Mum and baby held hostage in van on busy Jakarta street

Risma Oktaviani and her sleeping baby in the hands of Hermawan.

WARNING: Confronting content

Shocking scenes have unfolded on a busy street in east Jakarta after a mother and baby were held hostage at knifepoint in a mini-van.

On the night of April 9, a man, identified in local reports as 28-year-old "Hermawan", jumped onto a public bus before brandishing his knife and demanding passenger's money and valuables.

When the bus came to a stop at a traffic light, two passengers screamed for help and managed to escape, leaving 25-year-old Risma Oktaviani and her sleeping baby in the hands of Hermawan.

As a crowd gathered around the van and took images of the unfolding situation, traffic policeman Adjunct First Inspector Sunaryanto saw the commotion and began hostage negotiations with the offender.

Videos captured from numerous bystanders show Hermawan holding the knife at Oktaviani, who is cradling her sleeping baby. Visibly agitated, Hermawan yells at the growing crowd and orders them to disperse so he can make his getaway.

While some members of the crowd try to talk the man out of violence, others heckle him; "Be patient, you nut case," and "have you not eaten or something?"

Others called for him to be burned.

In the footage, officer Sunaryanto can be seen firing a shot at Hermawan, close range, hitting his right arm. Chaos ensues, and Hermawan is beaten by an angry mob.

"The culprit, however, refused to give in, even though he was panicky. After about half an hour of negotiation, the police decided to shoot him in his right arm," the head of the East Jakarta Police criminal unit, Sapta Maulana, told The Jakarta Post.

Oktaviani and her baby managed to escape safely, with mum suffering a small injury to her neck from the knife.

According to local reports, Hermawan was taken to National Police hospital where he was treated for his gunshot wound. He admitted he "often mugs women and uses the money to feed his gambling addiction".

Authorities said officer Sunaryanto will receive an award for his bravery.