International aid agencies are warning of an "unfolding humanitarian catastrophe" in parts of Somalia after recent fierce fighting in the capital.
Residents are fleeing on trucks, buses and donkey carts
The UN says about 90,000 have fled Mogadishu since Saturday and the worsening security means relief cannot be given to them.
And World Vision says the situation has "intensified" compared to previously.
This comes as Somalia faces further uncertainty after its prime minister, Ali Mohammed Ghedi, resigned on Monday.
World Vision Somalia's operations director Graham Davison who is based in Nairobi told the BBC's Network Africa programme that the situation in Mogadishu, "has intensified", and has "increased to a height that we haven't seen in previous occasions".
And about the newly displaced, Mr Davison said: "They're suffering without food, sanitation, without water, without shelter. And the majority of these people are women and children."
The BBC's East Africa Correspondent Karen Allen in Nairobi says the tone of the latest warning is alarming, especially because aid agencies are describing the violence over the last few days as the worst they have seen in months.
Ethiopian troops fired at protestors on Sunday
Many of the people fleeing their homes in the Somali capital, Mogadishu, after the fresh bout of clashes are heading west to the town of Afgooye, our correspondent says.
UNHCR estimates that 400,000 Somalis had fled Mogadishu by May this year, of whom about 125,000 later returned to the coastal city.
But then renewed violence in June sparked another wave of about 90,000 departures.
There are already 1.5m people who need assistance in the war-torn and drought-prone country.
Shells fell on Mogadishu on Saturday, Sunday and Monday as Ethiopian-Somali government troops and Islamist rebels battled.
And on Sunday, thousands were forced to flee from Ethiopian troops after they opened fire on protestors.
UNHCR says the level of militancy and intensity of the fighting has escalated as Ethiopian troops supporting the fragile Somali transitional government try to flush out insurgents.
It is feared that the uncertainty over who will replace Mr Ghedi will yield more violence.
Aides close to President Abdullahi Yusuf said that Mr Ghedi's resignation was part of a deal to end what he called the political confusion in Somalia.
But observers say the fear is that with Mr Ghedi gone, the Hawiye clan - the dominant one in Mogadishu and the largest in the country - will now be even more united in their opposition to Mr Yusuf's transitional government.