The agency is distributing food packages to some 3,000 of the most vulnerable people in Kaifoun, a town southeast of Beirut where at least 14,000 people are taking shelter in "transit centers" - public schools and other municipal buildings. Normally a town of 5,000 people, Kaifoun has swelled to 35,000 to 40,000 people in the last week, town officials tell Mercy Corps. 

We need your help to assist the elderly, the disabled, children, and the poorest of the poor affected by the ongoing violence. 

In coming days we plan to distribute additional emergency supplies to underserved villages and communities in the Shouf region southeast of Beirut, and work to ensure access to clean water. 

Agency officials in Beirut are also exploring ways to distribute food and other essentials to southern Lebanon. 

As fighting in northern Israel and Lebanon raged on, estimates on the number of displaced residents climbed to 500,000 and humanitarian concerns moved to the fore. 

UN humanitarian chief Jan Egeland told CNN on Tuesday that he's getting "reports of hundreds of thousands of people being displaced" from their homes in the wake of the violence. "Tens of thousands are already in schools and public buildings," said Egeland, head of the UN Office for the Coordination of Humanitarian Affairs. 

David Holdridge, Mercy Corps' Regional Program Director for the Middle East, based in Beirut, told CNN on Tuesday afternoon about large movements of people from the besieged southern Beirut suburbs to mountainous areas east of the city, where the agency's first relief distribution is taking place. 

He called on all parties to ensure access for humanitarian supplies and workers. "Displaced people without strong family networks are going to have serious humanitarian needs, and we are helping address those needs," Holdridge said. 

In southern Lebanon, which is generally less developed and more poor than other parts of the country, Mercy Corps works to improve agricultural and environmental practices in impoverished farming communities. These programs are on hold until the security situation improves. 

Mercy Corps has worked in Lebanon since 1996, investing in programs to improve agricultural practices, expand access to information technology, bolster tourism and manage natural resources. 

Help us deliver humanitarian aid to those most affected by the violence and respond quickly to emerging needs by donating Lebanon Crisis Fund.