By Sahal Abdulle
MOGADISHU (Reuters) - Shells pounded Mogadishu on Saturday, killing at least 73 people to swell a death-toll already in the hundreds from this week's battles between militant Islamists and allied Somali and Ethiopian troops.
The escalating war has also sent more than 321,000 residents -- nearly a third of Mogadishu's total population -- fleeing in the biggest refugee movement in Somalia since the 1991 fall of dictator Mohamed Siad Barre ushered in 16 years of anarchy.
Even by Somali standards, Saturday's carnage was shocking.
"I counted 20 dead in the street and the sidewalk. Some were missing heads, others were so mutilated you couldn't tell if they were men or women," resident Suleman Mohammed said from the Al Barakah market area where more than seven mortars landed.
Residents and medical staff interviewed by Reuters confirmed a minimum of 73 casualties from the incessant shelling and gunfire across the city on Saturday, adding to an estimated 131 others from the previous three days' violence.
The week's final death-toll is expected to soar and may come close to the estimated 1,000 casualties from a similar four-day flare-up at the end of March. Most of the victims are civilians.
The Islamists ruled most of south Somalia for the second half of 2006, before being defeated in a brief war over the New Year. But Islamist fighters -- backed by some disgruntled Hawiye clan elements -- have regrouped to rise up against President Abdullahi Yusuf's administration and his Ethiopian backers.
"There are a lot of deaths. I am carrying the bodies of two family members into my car now," one distraught resident, who asked not to give his name, told Reuters.
Another, Abdi Mohammed, said: "Six shells hit our neighborhood. One hit our neighbor's house killing five of the six family members who live there. My seven-year-old son and his friend were wounded."
The United Nations and aid agencies say the massive refugee exodus is also creating a looming humanitarian catastrophe, with diseases already striking. Many refugees are living under trees and beside roads, short of food, water and any basic amenities.
Inside the city, residents described a terrifying night of near-constant shelling mixed with thunder from a storm.
Mortars, apparently from Ethiopian positions, hit the offices of the private broadcaster HornAfrik on Saturday morning, wounding several journalists inside, witnesses said.
"We are in a state of shock, I see no end to this," said Ali Haji, 50, a resident who took his family out of Mogadishu last month but came back to protect his house and belongings.
"I've had enough. I'm abandoning the house. I am caught between two groups -- Ethiopians trying to kill me because I am Somali, and insurgents not happy because I am not picking up a gun and fighting with them. I have lost all hope."
With even a cemetery under bombardment on Saturday, residents buried their dead in makeshift graves.
The only operating hospital, Madina, was packed with wounded, screams echoing through the corridors. Tents were set up in the hospital garden to deal with the influx, with many people nursing injuries unattended under trees in the heat.
"Unless we get massive international help, we cannot cope," a doctor said. "Our beds and tents are full."
Access to the hospital involved a dangerous journey through streets ricocheting to gunfire and explosions, witnesses said.
Insurgents barricaded themselves behind makeshift sandbanks and raced through streets on the backs of pickups turned into battle-wagons, while Ethiopian and Somali troops made forays into rebel strongholds with armored cars.
A small African Union peacekeeping force of 1,500 Ugandan soldiers has failed to stem the conflict.
The United States, Ethiopia and Somali government say the rebels are linked to al Qaeda, but Islamist leaders deny that, saying they are being deprived of a say in Somalia's future.
(Additional reporting by Andrew Cawthorne in Nairobi)