A suspected smoke grenade explosion at Indonesia's national monument park, near the presidential palace in central Jakarta, has injured at least two military officials, the capital's top police official says.
President Joko Widodo was not at the palace at the time of the blast on Tuesday, a presidential spokesman said.
It was not immediately clear if the blast resulted from a sectarian attack but Indonesia, the world's most populous Muslim-majority country, has suffered a resurgence in home-grown militancy in recent years.
The park explosion was suspected to have been caused by a smoke grenade and two injured military officials had been taken to hospital, Jakarta's police chief, Gatot Eddy Pramono, told a televised news conference.
The two injured officers were doing exercises in the park at the time, Jakarta military chief Eko Margiyono said.
Asked if the blast was the result of an attack, Pramono responded: "We haven't concluded so because we're still investigating."
Earlier, Jakarta police spokesman Argo Yuwono told Kompas TV the "injured victims have been taken to hospital" but did not elaborate.
In November, six people were wounded after a 24-year-old university student blew himself up outside police headquarters in Medan.
The attack was linked to the Islamic State-inspired Jamaah Ansharut Daulah, responsible for a series of attacks across the country.
In October, a suspected Islamist stabbed and wounded former security minister Wiranto at a function to open a university building.