Colombian authorities say a homemade explosive has gone off in the capital's financial district, wounding five people.

Col. Oscar Pinzon of the Bogota Metropolitan Police says there is no information on who might have set off Thursday's explosion. He describes the device as of being of medium power.

No one has claimed responsibility for the blast, which comes at a time of increased tensions between the government and the country's biggest rebel movement, the Revolutionary Armed Forces of Colombia. Both sides in Colombia's long-running conflict have been stepping up attacks in recent weeks, jeopardizing the future of 2-year-old peace talks.

The explosion happened seven blocks from U.S. Ambassador Kevin Whitaker's official residence, where he was hosting dozens of people at a reception to celebrate the Fourth of July.