Colorado floods death may increase even further, warned Colorado authorities.

The historic flooding in the state already has four deaths verified, while two others are also presumably dead. The latest victim of the flood appears to be an octogenarian woman who lost her home in the floodwaters. Her house in Larimer County had been washed away, reported John Schulz, sheriff's spokesman.

Schulz further said that the woman had not been able to get out of her house due to injury. Nevertheless, when her neighbours tried rescuing her, they found the house was gone, he said. Another woman, 60, has presumably been killed in the flood. Her house, located in the Big Thompson Canyon area, was also swept away.

The reported four deaths in the flood consist of one in Colorado Springs and three other in Boulder County. On the other hand, over 500 people are still missing in Larimer and Boulder counties, according to authorities. President Barack Obama has already declared the area a federal disaster.

There was further rainfall in the state on Sunday, which was instrumental in slowing down the search process significantly. In addition to death and hundreds of unaccounted people, the massive flooding is responsible for an interrupted communication system as well. The mobile phone towers have been damaged, while there have been power outages due to the flood, which affected the telecommunication system in the locality.

Colorado Governor John Hickenlooper said that many houses had been destroyed while several others collapsed. Thousands of people have, meanwhile, been evacuated when heavy downpours flooded the roads and swept away communities. Governor Hickenlooper said that more rain was expected, making the situation more dreadful.

On the other hand, U.S. Army and U.S. National Guard rescued 1,750 people from the mountain canyons of Larimer and Boulder counties, stated Army spokesman Major Earl Brown.