(Ferguson, MO) -- Protests are once again turning violent in Ferguson, Missouri. Police fired tear gas into a crowd of around 100 demonstrators when they failed to follow an order to disperse. There are reports that some protestors threw bottles in the direction of police lines. It's the fourth night of protests in the wake of the police shooting of an unarmed black teenager over the weekend. Earlier, Ferguson Police Chief Tom Jackson urged protestors to hold their rallies during the daytime, but stopped short of calling a curfew for the St. Louis suburb.