CARTAGENA, Colombia - Two small bombs exploded in Colombia's capital Bogota on Friday, and police said they may have been a protest by leftist guerrillas against the presence of US President Barack Obama elsewhere in the country for the Summit of the Americas.

"There are windows broken, but nobody hurt or killed," a senior police source told Reuters, saying the explosives were placed in a ditch in a residential area near the attorney general's office and the US Embassy.

Obama landed in Cartagena, on Colombia's northern coast far from Bogota, earlier on Friday.

"It might be a protest by an urban guerrilla cell against Obama," the source said.

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