MSNBC and NBC News reports fours small bombs exploded in Colombia, after Obama arrived for the Summit of the Americas.
According to CNN, two small explosions took place in Cartagena, far from where the world leaders gathered for the beginning of the Summit, one near a bus station and the second near a shopping mall.
Two further bombs exploded near the American embassy in the capital Bogota, as reported by EuroNews. They also report police say they may have been planted by leftist rebels.
It is also reported no one was killed or injured in the attacks.