Sorry to hear about your chickens but it does sound like they were attacked by africanized bees. One problem most people dont know is that , as stated in another post, they have found that normal honey bees are also showing more aggression towards percieved threats, whether its people or animals. As someone else stated, and scientists have speculated, that honey bees are mixing with african bees and cross breeding. Also, they have done tests to see how cold a african bee can stand and have shown that they will cluster to keep warm, which shows incredible intellengence. They fear, within a time span of 10 to 15 years, honey bees as we know them will be extinct and we will have a more agressive bee to deal with. Personally, I think they should ban importing species that are not indeginous<sp> to another country. This all started in South America. One day, some worker decided to remove the queen excluders that kept the queens in the hive, and now, we have bees migrating this way, further and further into our country, putting people and livestock at risk. You can get rid of the bees, but you better make sure its a qualified professional and tell them you think they are africanized for thier safety. Please be careful so you and your family arent the next victims.
P.S. I saw a story about all this on National Geographic or Discovery Channel on these bees and thats where I got my information.
Rammy