Violent Portland protests were once again declared a riot Monday night as Black Lives Matter militants tried to torch a police union building while chanting, “Burn it down.” Around 300 people — many wearing shields, gas masks and body armor — stormed the Portland Police Association Building as rocks were thrown at officers, according to police. “Power to the building was cut and flames were seen shooting up the side of the building,” the Portland Police Bureau said — just a night after a fire had been set at a precinct late Sunday.