At least seven people were killed on Thursday when militants attacked a Starbucks and a police post in the Indonesian capital of Jakarta.

The assault took place in front of the Sarinah shopping mall, where it was reported that several suicide bombers detonated themselves. Some of the assailants reportedly engaged in gun battles with police. Four of the attackers were among the dead.

It was not immediately clear who was behind the attacks, although local broadcasters showed images of blood-soaked people lying on the ground. One station, TVOne, reported a policeman and a suicide bomber were among the three people killed.

AP subsequently quoted TVOne as saying that explosions had also taken place in near the Turkish and Pakistani embassies.

A chaotic scene

Witnesses who were there described a chaotic scene, saying Indonesian security forces had engaged in a gun battle with some of the attackers.

A UN regional representative, Jeremy Douglas, tweeted that at least one blast took place in front of a UN office in the capital.

Douglas said police were broadcasting announcements for people to stay away from windows.

"We went down and saw three people lying dead, and also two foreigners badly injured but still alive," Ruly Koestaman told German news agency DPA.

Public warned to stay away

Indonesian President Joko Widodo told the public to remain calm, saying the situation was under control.

"The state, nation and people should not be afraid of, and lose to, such terror acts," Widodo said.

AFP said national police spokesman Anton Charliyan had warned the public to stay away, saying police feared there could be more bombs.

"For now the gunfire has stopped, but they are still on the run. We are afraid there will be more gunshots," Charliyan said.

Helicopters circled the downtown area, which had been cordoned off, and heavily armed police had evacuated a badly injured man on a stretcher.

A mobile phone video taken from a high-rise building showed one of the explosions followed by smoke billowing from the location.

The area around the mall also has many luxury hotels, embassies and offices.

Already on edge

Indonesia, the world's most populous Muslim-majority nation, has been on edge over recent weeks as police cracked down on people with suspected links to the militant group "Islamic State."

At New Year's, Indonesia was placed on high alert and authorities said they had foiled a plot by Islamic militants to attack government officials, foreigners and others.

At the time, about 150,000 police officers and soldiers were deployed to safeguard churches, airports and other public places.

In 2009, twin hotel bombings in Jakarta claimed the lives of seven people.

blc/ij/rc (Reuters, AFP, AP, dpa)