A SpaceX rocket has exploded after test-firing at Cape Canaveral, USA - photo by USA Launch Report video

A SpaceX rocket exploded during a test fire prior to launch at Cape Canaveral, Florida, USA today. SpaceX officials said that "an anomaly" occurred while the rocket was being fueled. 

The rocket was carrying an Israeli-made communications satellite, called Amos-6,  for Facebook that was going to be sent into space to provide internet connection to some parts of sub-Saharan Africa. 

SpaceX is an aerospace manufacturer and space transport services company headquartered in Hawthorne, California, United States that was founded by Paypal co-founder, and Tesla Motors CEO, Elon Musk. 

prior - before
to launch - the act of sending something into flight

anomaly - something that is not normal and very rarely happens
to fuel - to put fuel (material energy) into a vehicle 
aerospace - related to aircraft flying into outer space (space beyond the earth's atmosphere)