CAIRO (Agencies) - Columns of thin smoke were still rising from the upper house of the Egyptian parliament on Wednesday, a day after a fire gutted much of the three-story palace, including the 19th century building's historic halls and its archives, according to The International Herald Tribune. Egypt's general prosecutor has opened an investigation into the cause of the fire. Initial reports suggested that a spark during maintenance work on Tuesday afternoon might have ignited the blaze, a security official said. He spoke on condition of anonymity because he wasn't authorized to speak to the press. One firefighter is missing and believed to be dead, a security official said. At least 16 workers and firefighters were hospitalised for smoke inhalation and other minor injuries, said Ahmad Salah, the fire operations supervisor. Meanwhile, the government is ruling out arson or terrorism in the fire, Interior Minister Habib el-Adli said on Wednesday. "The security agencies are ruling out the possibility that any terrorist act or deliberate act was behind the incident," he added, quoted by the state news agency MENA. Police sources said in the early stages of the fire that they suspected it began with an electrical short circuit.