Obviously they were bees. They swarmed around the front of our house for a minute or two and then started landing on an inside branch of a pygmy date palm in our front yard. After about 15 minutes there was a huge squirming mass of them formed into a ball.
We were worried because there are many kids and families who walk in front of our house every day. We called the city thinking they would send someone out to take them away. Wrong! The lady said to leave them alone. She also told us that bees swarm like this because a "new" queen has been born and the colony must split up. They are only looking for a new home. They don't want to stay in a palm tree, so they are just spending a day or two until they find a more suitable place to live. In the meantime, because this isn't their "real" home, they aren't territorial and won't be aggressive at all. They won't sting anything or anybody, unless they are attacked. Leave them alone was her advice.
We left them alone and the next morning I watched them start to buzz around and then fly away. Once they started to leave, it only took about two minutes until everyone of them was gone.
I was happy to see them go, because I've been stung many times in the past. Somehow I manged to avoid it this time...