Six people were killed in nearly simultaneous explosions at the Ritz-Carlton Hotel and the Marriott Hotel in central Jakarta on Friday, Indonesian police said.
Jakarta police spokesman Chrysnanda Dwilaksana said he could not confirm if the blasts were caused by bombs. A Jakarta hospital official said 10 people had been brought in for treatment.
There have not been any major bomb blasts in Indonesia for several years, and this month the country's presidential election passed off peacefully.
We know there are six victims, six who died and there are several others injured and we have evacuated them to hospital, Dwilaksana said.
The Indonesian rupiah fell 0.7 percent to 10,200 per dollar after the explosions, prompting state banks to sell dollars to support the currency, traders said. The stock market has not opened yet.
Witnesses at the scene told Indonesian Metro TV that the injured, including Indonesians and foreigners, were seen being taken away in ambulances.
Some windows of the Ritz-Carlton building have been shattered, mostly on the lower section. I'm looking at it from my office, said Myra Junor, who works at a nearby building.
Lydia Ruddy, a witness who lives in the area, told Reuters she could see debris everywhere.
She said she heard an explosion and saw smoke coming from the Marriott, followed five minutes later by another explosion at the Ritz-Carlton hotel, which is in the same area.
An Australian man told local Radio 2UE his son had been hurt at the Marriott and was being taken to hospital.
The Marriott Hotel was badly damaged by a car bomb attack in 2003 that killed 12 people.
That coincided with a period when Islamist militants from the Jemaah Islamiah organization were blamed for numerous attacks, including bombings on the island of Bali in 2002 that killed 202 people. Many militants have since been arrested.