Fireworks at or before dawn are common in Mexico. I even heard them recently in Mexico City at about 5AM! The fireworks are petitions to the gods for intercessions or for celebrations of feast days, birthdays, deaths or whatever is important to someone - hence, lots of fireworks. BUT most of the times they are off in the distance - not always.
One early morning, about 4:30AM I woke to the sound of singing.......I laid there a minute to make sure I was awake and not dreaming and it continued........so my curiosity got the best of me and I went up the four flights of stairs to the roof terrace to see what was going on. Down below me on the road was a group of people with a white banner with the Virgen on it facing toward the canyon. They were singing "las mananitas" and it was this pure, gentle sound. So I watched unobserved for quite a while and when I started to get cold I came back in and got back under the covers. By now it was about 5:30AM and all of a sudden this "tuba band" started up and the singing got louder. As I listened, I heard the tuba band play "My heart belongs to you" and I just giggled and smiled and went back to sleep. Just one of my precious memories of living in this beautiful country!