The fire broke out at 4 pm and was brought under control after some time. The exact cause of the accident could not be ascertained, HPCL officials said.
Two workers were killed in the accident and 37 people were undergoing treatment at various hospitals, out of whom the condition of three to four persons was stated to be critical, they added.
As per initial reports, the fire broke out due to blasting of cooling tower due to short circuit. A majority of the injured workers belonged a private firm working for the cooling tower.
A thick layer of smoke engulfed the area causing panic among nearby residents. They said they heard a massive sound from the scene and plumes of smoke billowed out of the area.
Fire tenders from all over the city were pressed into service to control the fire. The injured persons were shifted to various hospitals, including the INS Kalyani.
Andhra Pradesh Chief Minister N Kiran Kumar Reddy expressed anguish over the incident and conveyed his sympathies to the bereaved families.
He directed the District Collector and the Police Commissioner to take up rescue operations and provide necessary medical assistance to the victims.
Meanwhile, Andhra Pradesh Infrastructure and Investment Minister Ganta Srinivasa Rao asked the officials to shift the injured to corporate hospital for immediate treatment.
He asked the joint inspector of factories to conduct a preliminary investigation into the incident.
In September 1997, fifty six workers were killed in a major fire accident in the refinery due to spark in LPG pipeline between port and Vizag refinery.