Here is Mark L. Winston's account of meeting Africanized honeybees in South America, from his book Killer Bees :

My 1977 visit to an apiary in Surinam that had recently become Africanized was typical. A local schoolteacher maintained about twenty colonies in an isolated grove out in the country, a few hundred meters away from a number of small farms. He abandoned his colonies shortly after my visit, but at that time he was still keen on beekeeping and eager to convince me of the advantages of these bees. Even so, we parked about a half-kilometer from his beeyard, put on two layers of clothes under our bulky beesuit coveralls, and carefully secured our veils and gloves to leave the bees no room to enter. Then we lit the largest smokers I had ever seen, bellows-like instruments that burn burlap, old sheets, cardboard, dried cow patties, or whatever else is available to generate smoke to pacify the bees. Only then did we approach his colonies, and I should have been warned by these elaborate precautions.

Merely walking toward the colonies elicited a massive response on the part of the bees, so that the situation was out of control before we smoked and opened our first colony. Bees were everywhere, banging into our veils and helmets with such ferocity that we could barely hear each other and stinging through our layered clothing. It was a hot, humid day, and the combination of sweat, noise, and stings forced us to retreat after examining only a few colonies. The bees followed us all the way back to the car, and we had to keep our equipment on until we were far out of the stinging range. As we drove off, we could see the farmers swatting at bees and two of their cows were being stung; we had to stop and move the animals farther away to safety.

Fortunately, no one was seriously hurt, but this incident was not unusual. There have been frequent deaths of livestock that are fenced or chained too close to Africanized hives, and there have been some human fatalities due to massive numbers of stings. On this occasion I received over fifty stings in just a few minutes, in spite of my heavy beekeeping armor, and I could only imagine what a full day of working with these bees would be like.