Eighteen patients died at a hospital in the southern Indian city of Chennai after rains caused a power outage, affecting ventilators, officials said Saturday. The death toll from torrential rains that triggered floods crossed 280 late Friday.

State authorities are reportedly investigating complaints of negligence by officials at MIOT International hospital in the city hit by massive floods. The deaths occurred despite Tamil Nadu state's Health Secretary J Radhakrishnan saying Thursday that all the city hospitals were safe and safety of the patients had been ensured, according to the Indian Express, a local news outlet.

Radhakrishnan reportedly said that the 18 patients died over a span of three days after floodwaters entered the rooms affecting generators and cutting off power to the hospital building.

Chennai_1 Indian people walk through through floodwaters on a street in Chennai on Dec. 4, 2015. Photo: Getty Images/STR/AFP

Army soldiers were carrying out rescue operation Saturday despite flood waters rising again around noon after a new cloudburst. Chennai's airport remained closed for a fourth day Saturday, although some flights operated from a nearby air force base. Road transport was also affected as most of the areas were submerged in water.

Chennai 4 Indian army personnel use a boat to rescue residents from floodwaters in Chennai on Dec. 3, 2015. Photo: Getty Images/STRDEL/AFP

On Saturday, the government deployed hundreds of additional soldiers and relief workers to the flood-hit city after facing criticism that relief had not reached several neighborhoods where many were stranded without any food and shelter.

Chennai_2 Indian volunteers distribute packets of milk from the back of a vehicle to flood affected residents in Chennai on Dec. 5, 2015. Photo: Getty Images/STRDEL/AFP

Large parts of India's fourth-largest city were inundated by up to 8 feet of water after torrential rains that began earlier this month.

"We are asking for more help from the army, the national disaster relief team," Atulya Mishra, relief commissioner of the state of Tamil Nadu, reportedly said. "It has been a monsoon unlike anything we have seen in history, we need all the help we can get."

Chennai 3 Indian army personnel deliver supplies to residents trapped by floodwaters in Chennai on Dec. 4, 2015. Photo: Getty Images/STR/AFP/

Indian Prime Minister Narendra Modi surveyed the flood-affected areas of Chennai, Kanchipuram and Tiruvallur districts in Tamil Nadu Thursday and announced a relief fund of $141 million.