It seems to be open burning, but, is it?

As I saw a lot of smoke from a distance. It looks like a big fire breaking out. The smoke was getting thicker.

Lots of black some, then as I zoom in, saw fire here and there, what seems to be a classic open burning scenario. Then I heard the fire engine siren, holding my hand as steady as possible.

After a while, the fire at the location seems to have died down, but the smoke was still a lot. Then, it seems like fogging smoke. Am confused, but then it could be the relevant party is doing their job of taking down the area with lots of mosquitoes. Maybe it is not open burning? 

I am still not sure what it was. Because I don't see people running out of their homes. The fire seems like it just died down on itself. And then, after all the smoke subsides, seems like fogging activities. I am leaving the video for you to judge. It could be an accidental open burning, or it could be a planned burning by the authorities.

 Location is somewhere around Kampung Cheras Bahru.