Michele Kelemen

The great mystery behind what hurt two dozen U.S. diplomatic personnel in Cuba remains unsolved, according to a Senate hearing on Tuesday. But an FBI investigation is casting doubt on a once-popular theory: that embassy staff were the victims of "sonic attacks."

According to a report seen by the Associated Press, an FBI investigation has turned up no evidence that sound waves harmed American diplomats in Havana.

Health officials have warned that if aid doesn't arrive soon to West Africa, more than a million people could be infected with Ebola by late January.

Last week President Obama announced plans for a surge in U.S. aid to the region. The U.K. and the European Union followed suit.

The United Nations is also gearing up to provide aid. Representatives from member states met Thursday at the U.N. General Assembly to tackle the crisis.