In a busy downtown military hospital in Jakarta, security was tight as nine of the 24 wounded received medical treatment after Thursday's attack by militants linked to the Islamic State in Iraq and Syria.

Relatives of some of the victims were at the waiting area outside the intensive care unit, with military officers guarding the entrance, The Straits Times observed.

Officers were also monitoring various sections of the hospital, where those injured were reportedly warded.

The tension had eased after the sudden chaos that broke out on Thursday, when five militants launched an attack outside a Starbucks cafe near the Sarinah mall.

Local press reported that two of the wounded housed at RSPAD Gatot Subroto, the military hospital, were in intensive care.

One of them, Dutchman Yohanes Antonius Maria, 52, was reported initially as being in critical condition. The Straits Times learnt that Mr Maria, a United Nations officer, was conscious and stable as of yesterday afternoon.

The government announced it would bear the medical costs of those injured in the attack, presidential spokesman Johan Budi told reporters.

The blasts and ensuing shoot-out left seven dead, of whom five were the attackers. The remaining two killed were reported by the local authorities to be civilians - a Canadian and an Indonesian. The Canadian Embassy has yet to confirm the deceased's citizenship.

About 20 bystanders and five policemen were injured in the attack.

Among them were two siblings who were crossing the road from the mall, Detik news reported.

One of them saw an explosion at the Starbucks cafe before being hit by the blast at a nearby police post. "After that, I don't know what happened," said Mr Muhammad Nurman Permana, who also heard several explosions within the area.

Mr Nurman and his sister Agus Kurnia are receiving treatment for their injuries.

Another of those injured, Ms Mira Puspita, told reporters that the suicide bomber in Starbucks was walking back and forth in the cafe before the explosion occurred.

"The explosion came from the washroom," Ms Mira, who was a patron at the cafe, told SindoNews. She added that Mr Maria was seated behind her when the first blast went off.

Indonesian President Joko Widodo made another visit to the attack site yesterday and told reporters that all had returned to "normal".

The most recent previous militant attacks in Jakarta were in July 2009, when bombs went off at the JW Marriott and Ritz-Carlton hotels.