25 fire-tenders have been pressed into service to douse the flames that broke out on the fourth floor of Navjeevan Complex, fire officer Ishwar Jat said.
The fire is suspected to be caused by a short-circuit, he said, adding that one fire fighter sustained injuries while extinguishing the flames.
Meanwhile, people from neighbouring areas have been evacuated and traffic near the complex is diverted as a precautionary measure, Police Commissioner B L Soni said.