At least 20 people have died in flooding in north-eastern Brazil after some areas saw more than 36cm (14 inches) of rainfall in three days. Officials said 10 people were killed in the state of Alagoas and another 10 in neighbouring Pernambuco. Fifty-thousand people have fled their homes and some municipalities have been declared a disaster area. Civil defence officials said the flooding in some parts was so bad, residents could only travel by boat. Emergency workers are airlifting people out of the worst-affected areas by helicopter. In Pernambuco, five members of one family drowned when the flood waters rose too fast for them to reach safety.