( CNN ) -- The knock on the door is a sign of bad things to come . `` Do you have any work ? '' they ask . They have fled their villages and come into the city out of desperation . Their bellies ache from hunger . `` For those of us in the city , we are seeing the first signs of food crisis spreading across our country . We have seen it before . It has already started , and it is coming fast . '' That 's what Haoua Lankoande , a manager with the humanitarian agency CARE wrote in a recent blog post from the Niger capital , Niamey . The first phase of hunger drives villagers into the city ; the second phase brings knocks on the door , Lankoande wrote . `` Do you have any food ? '' they ask . `` I have n't eaten in three days . '' Eventually in phase three , Lankoande said , people do n't ask anymore . `` You wake up and go outside in the morning , and there is a family sleeping on your doorstep . They do n't ask for anything , they just look up at you , hoping . '' CARE and other aid agencies fear Niger is already in the first stage of crisis . It does n't take long , they say , for the situation to deteriorate from phase one to three . `` What we are seeing is a tip of the iceberg , '' said Cassandra Nelson , spokeswoman for Mercy Corps . Nearly half of Niger does not have enough to eat . The 5.4 million people struggling to stay alive are part of a wider crisis affecting at least 10 million people across the swath across Africa that borders the Sahara , known as the Sahel . This is the third time in the last decade the people of the Sahel have faced severe food shortages . The problem , caused by drought and high food prices , is exacerbated by an ongoing conflict in Mali between the military and Tuareg rebels that has forced people to flee into neighboring nations . Niger , Mali , Chad , Burkina Faso and Mauritania are all facing hunger . All five governments have declared states of emergency . In Niger , people depend on crops and livestock for survival . They are used to living life on the edge . Every year , life is a gamble . In the dry months , they prepare for what is known as the `` lean season . '' They eat once a day or maybe even once every 36 hours . Typically , said Nelson of Mercy Corps , the lean season begins in May . This year , it has already arrived . Premature and deadly . This week , a United Nations delegation arrived in Niger to size up the horrific situation . `` We know what is coming , and we know what to do to save lives , '' said Valerie Amos , the U.N. emergency relief coordinator . `` While we can not stop this crisis from taking place , we are taking steps to avert a catastrophe . '' Amos said international aid agencies have called for about $ 725 million to respond to the crisis . Donors so far have provided $ 135 million . `` But we need more resources now to prevent a large-scale crisis , '' she said . In the hard-hit Filengue region , the images are stark . A woman with skin as black as her dress is white surrounded by shades of parched earth . Around her , rows of millet and sorghum that no amount of water could save now . The rains came late and locusts and crickets damaged crops . The next harvest is n't until October . People grow more desperate by the day , Nelson said . A bridge stands over a river of crevices . People dig up the river bed , hunting for the last few drops of water . They rely now on God and authorities , one man told the United Nations World Food Programme ( WFP ) . The agency said it has enough emergency food in the area to feed 2 million people in the Sahel for a month . It hopes to reach 8 million people in the coming months . Dije Ousmana told CARE she tries not to think of the three babies she has lost in previous years when food was hard to come by . But she is seeing all the wretched symptoms of hunger again in 2-month-old Abdulahadi , wailing to be fed . She put her baby to her breast but there is no milk , she told CARE . `` I have n't eaten yet today . '' CNN 's Joseph Netto contributed to this report .
Aid agencies fear the situation will deteriorate rapidly . Drought has led to a failure of crops . In all , 10 million people in the Sahel region are at risk .