- Several explosions reported in Indonesian capital
- Gunfire heard following explosions
- At least six people feared dead
Police said they suspected a suicide bomber was responsible for at least one of the blasts and up to 14 militant gunmen were involved in the attack.
The head of the national intelligence agency told Reuters there was no indication that Islamic State militants were responsible.
"This is definitely terrorism but there are no indications yet that it's ISIS related," Sutiyoso said.
Indonesia has been on edge in recent weeks over the threat posed by Islamist militants and counter-terrorism police have launched a crackdown on people with suspected links to Islamic State.
"We have previously received a threat from Islamic State that Indonesia will be the spotlight," police spokesman Anton Charliyan told reporters. But he said police did not know who was responsible.
He said three policemen and three civilians had been killed.
"I saw a police officer shot right in front of me," one witness said.
One explosion went off in front of a shopping centre called the Sarinah mall, on a main avenue. Media said a police post outside the mall was blown up.
Indonesian President Joko Widodo has condemned the attacks and conveyed his condolences to the victims of the but said he doesn't want to speculate on what was behind the blasts and has asked that others refrain as well.
President Widodo has urged people to give police a chance to investigate and track the perpetrator and mastermind of this terror.
Police snipers were deployed among hundreds of other security officers following the blasts. A UN building near the scene was in lockdown with no one allowed in or out, a witness said. Some other high-rise buildings in the area were evacuated.
Indonesia's central bank is located in the same area, and a spokesman for the bank said a policy meeting was going ahead and a decision on interest rates would be announced as planned later in the day.
An explosion was heard in the western suburb of Palmerah, according to a domestic media tweet, but police said they could not confirm a blast there. Indonesia has the world's largest Muslim population, the vast majority of whom practise a moderate form of the religion.
The country saw a spate of militant attacks in the 2000s, the deadliest of which was a nightclub bombing on the holiday island of Bali that killed 202 people, most of them tourists.
Police have been largely successful in destroying domestic militant cells since then, but officials have more recently been worrying about a resurgence inspired by groups such as Islamic State and Indonesians who return after fighting with the group.
The last major militant attacks in Jakarta were in July 2009, with bombs at the JW Marriott and Ritz Carlton hotels.
