Authorities in Ecuador say a bomb has exploded outside a branch of U.S.-based Citibank.

Police say the explosion took place Wednesday in the city of Guayaquil.

They say no one was injured, but the explosion blew out windows in the front of the bank, which was located near where free trade talks were being held between Colombia, Ecuador, Peru and the United States. 

It is not known who was behind the bombing.

Some information for this report provided by AP, Reuters.