BAGHDAD: A fire at a key oil refinery killed one worker and injured six others on Monday in northern Iraq, authorities said. The fire erupted at an upgrading unit in the Baiji refinery, once the country’s largest oil refinery, in Salaheddin province. The Iraqi government’s security media unit said in a statement that firefighters had extinguished the fire. It added that “one worker was killed and six others were injured.” Local official in Baiji city Adel Al-Daj told AFP that the explosion was caused by a technical malfunction.