NEW DELHI, June 26 -- Four people died and three were injured after a massive fire broke out at an illegal four-storey factory building in north-west Delhi's Rithala on Tuesday evening, police said, adding that over 100 firefighters worked through the night to bring the blaze under control after a 13-hour operation. The fire erupted around 7.30pm at Rana Complex in Budh Vihar, on the mezzanine floor between the ground and first floors, before spreading rapidly to the upper levels. All four floors were used for manufacturing or storage - from plastic bags and perfumes to disposable goods - and were engulfed within minutes, leaving several workers trapped. The four victims are believed to be those initially reported missing, but police said DNA tests will be conducted to confirm their identities, as the bodies were severely charred. A case has been registered under sections 287 (negligent conduct with respect to fire), 125A (act endangering life), and 105 (culpable homicide not amounting to murder) of the Bharatiya Nyaya Sanhita (BNS). The cause of the fire is under investigation. Fire officials said the building was not fire-safety compliant and operated outside the purview of any regulatory authority such as DSIIDC, MCD or DDA....