A CHEMICAL inferno belching clouds of potentially toxic smoke triggered an early morning closure of schools and roads in Canberra's northern suburbs yesterday. Police ordered the evacuation of more than 200 campers at 2am as blasts from transformer oil fuelled official fears of lethal mustard gas emissions. The blasts rocked the industrial suburb of Mitchell, sending flames as high as 200 metres, prompting emergency services to send SMS warnings for residents to stay indoors. Authorities initially ordered a 10-kilometre exclusion zone, the closure of about 50 schools and a halt to local bus services. The fire, at a factory that has a 300,000-litre storage tank and 10 45,000-litre tanks, was finally put out last night about 22 hours after it had begun.