Well, I haven't heard anything about teargas - the police just charged the crowd with shields and batons to clear the square and then chased the protesters on the nearby streets. The "homemade bombs" that the media are referring to are not Molotov cocktails, but more like the firecrackers football hooligans use. (By the way, one of the groups of protesters that acted hostile towards the police from the very beginning are said to be "ultras", the kind of football fans that consider picking up fights with the police a hobby.)

Anyway, one of the reasons the media don't connect the protest with the gas crisis is because the protest was scheduled in December, before the crisis broke out. The farmers and the students protested in the last day before the Parliament shut down for the holidays. (The students, because the death of a student made them realize what kind of a mess is Studentski Grad, and the farmers, because... well, I think it's something to do about subsidies.) But our glorious MPs voted to finish early that day, which pissed a lot of people off - it doesn't make much sense to protest if you don't have someone to protest in front of. So, a new protest was scheduled for the 14th of January and some other people decided to jump on the bandwagon. The gas crisis certainly increased the tension, but it wasn't the main motive. Another contributing factor was a proposed change in the law that would severely restrict future protests (e.g. the area around the Parliament would become a no-protest zone.)

(I hope my English is not very bad, I've been badly out practice since I graduated from high school.)