Transitional Libyan government forces swept into Sirte on Saturday in one of the biggest assaults yet on Muammar Gaddafi's hometown, but had to seek cover when they drew fire from his diehard loyalists.
Fighters with the National Transitional Council (NTC) shouted "Allahu Akbar!" or "God is greatest!" as their force of about 100 pick-up trucks mounted with heavy weapons pushed into a residential district on the southern side of Sirte.
They were forced to scramble for refuge under heavy fire from pro-Gaddafi fighters holed up in an apartment complex, a Reuters reporter on the scene reported. Two NTC fighters were killed and three wounded in the exchanges.
"There is a very vicious battle now in Sirte," NTC chairman Mustafa Abdel Jalil told reporters in the capital Tripoli, where he was meeting visiting defence ministers from Britain and Italy.
"Today our fighters are dealing with the snipers that are taking positions and hiding in the city of Sirte."
Taking Sirte would bring Libya's new rulers closer to their goal of establishing control of the entire country almost two months after they seized the capital Tripoli, but they are also under pressure to spare the civilians trapped inside.
The NTC forces have thrust Gaddafi loyalists back from defensive positions well outside Sirte, and are now contesting control of the centre of the city in often-chaotic, street-by-street battles.
The prolonged struggle to capture the few remaining bastions of pro-Gaddafi loyalists has sidetracked NTC efforts to set up effective government over the sprawling North African country and rebuild oil production vital to its economy.
Thousands of civilians have fled Sirte as fighting has intensified, describing increasingly desperate conditions for those still inside the seafront city.
There is no electricity while drinking water and food are running out, and people have spoken of the stench of rotting corpses at the city's hospital.
More residents were leaving Sirte on Saturday. "We could not understand who was firing," said Milad Abdul Rahim, who was heading out of Sirte. "It is just random."
Hassan Massoud drove out of the city in a pick-up truck with his family in the cab and luggage teetering on the back. He said he had decided to leave after his neighbour's house was hit.
"It was single-storey. It collapsed on them. It killed a man and a girl," he said.
Along with the interior desert town of Bani Walid, Sirte is one of the last redoubts of Gaddafi loyalists in the country he ruled alone for 42 years.
It holds symbolic importance because Gaddafi turned it from a fishing village into a second capital. He built opulent villas, hotels and conference halls to house the international summits he liked to host there.
But Sirte presents a particular challenge for Libya's new rulers. A drawn-out battle with many civilian casualties will breed hostility that will make it very difficult for the NTC to unite the country once the fighting is over.
The senior U.N. official in Libya, Ian Martin, appealed to NTC fighters on Friday not to aggravate those tensions by exacting violent revenge against Gaddafi supporters in Sirte.
For the anti-Gaddafi fighters, their offensive in Sirte has turned into a deadly game of cat-and-mouse with snipers.
Pro-Gaddafi forces stationed snipers in the Ouagadougou conference centre -- where the deposed leader used to host Arab and African heads of state -- and the university and hospital.
More snipers were in residential buildings in the north-eastern corner of Sirte. Faraj Leshersh, an NTC fighter in that sector, said the snipers were expert at operating unseen.
He said they used trenches between buildings which allowed them to move location without showing themselves. At other times, he said, they burned tyres so the smoke would conceal their movements.
A sandstorm on Saturday gave them cover to regain a little of the ground in the northeast of the city that they had earlier lost to the NTC forces.
"They (pro-Gaddafi forces) took advantage of the dust and they advanced a little. There is 500 metres (yards) between us and them," Leshrsh said from a luxury hotel now being used as a base to attack the city.
Another anti-Gaddafi fighter said that instead of sending in men on foot to locate the snipers, the NTC forces were now identifying their firing positions from a distance and blasting the buildings where they were hiding with heavy weapons.
"What made us tired is the snipers," said the fighter, Abdelsalam al-Rishy. "We're now using RPGs (rocket-propelled grenades) to deal with the snipers."
At a field dressing station just west of Sirte, doctors were treating wounded NTC fighters.
One of the wounded, Mohammed Gallous, was bleeding from a head wound sustained when a mortar landed near him. He was asking people nearby if his ear was still attached to his head.