Four explosions in Colombia; target Obama?

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.

Two other low-intensity blasts occurred in Cartagena where the summit is being held.

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

Obama landed in Cartagena, on Colombia's northern coast far from Bogota, earlier on Friday. A senior military official says two bags of gunpowder exploded in a vacant lot about a quarter mile (400 meters) from Cartagena's bus station on Friday evening. The official spoke only on condition he not be further identified.

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