Describing the floods as the worst in 70 years, Sudan's media warned of more agony for the city’s half a million residents as the river Nile continued to rise menacingly.
With an average Sudanese family comprising six members, it is estimated that up to 420,000 people in the city some 450 kilometres east of Khartoum could be without shelter.
Newspapers put the toll at 13.
Though other regions of Sudan have been experiencing heavy rains, Kassala has taken the worst pounding.
Flood waters have submerged part of the highway between Khartoum and Port Sudan, the country’s main port. Gushing flood waters have overturned several vehicles on the road.
Interior Minister Abdel Rahim Mohamed Hussein urged people to take “all necessary precautions to deal with the level of the Nile, which registered a greater rise than in the past few years.”
Floods sweep Sudan periodically with devastating effects.
In 2001, heavy flooding of the Nile and torrential rains in southern Sudan made thousands homeless.
In 1988, dozens of people were killed and two million lost their homes after the Nile burst its banks.