Four labourers were killed in a fire that broke out in a shoe factory here on Monday, said a fire officer.The blaze started at the Raja Park factory in Sultanpuri at around 6.35 a.m. There were around a dozen labourers inside the factory when the fire broke out, the Delhi Fire Service officer said. Nine fire tenders were rushed to the spot."Four labourers, who were trapped inside it, died due to suffocation and burnt injuries. They were rushed to the Sanjay Gandhi hospital. Efforts are on to identify the deceased," he added.The fire which broke out due to a short circuit, was doused at 9.50 a.m., the officer added.