Any contact with an exterminator or bee removal service is the responsibility of the person calling. Remove any pets or children playing in the area and have them stay inside a building. Encourage people in the area not to make noise. Bees are especially attracted to lawnmowers, dogs barking, weed eaters or other humming noises. They are also attracted to bright flashing lights.
Bees swarm in the spring and fall.
If you get too close, you may get stung, but most likely will not be attacked. The swarm is actually taking a rest and will move on to find a place to build a hive in a remote, safe location. If the swarm is on your property you should have it removed. The bee hive is where the bees live. When the bees feel that their hive is threatened, they will protect it aggressively.