Editor's note: Watch CNN's special on the brutal Syrian crackdown, "Homs: City Under Siege," first airing at 5.30 a.m. ET Saturday on CNN International and at 10.30 p.m. ET Saturday on CNN US, and repeated through the weekend.
(CNN) -- In the ancient Syrian city of Homs, locals used to enjoy a vibrant café culture and relatively easy living.
The city was a Syrian success, a center for agriculture, oil and trade; a home to Shia, Sunni and Alawite Muslims as well as a small Christian community among its one million people.
The road through Homs connects Syria's largest city, Aleppo, in the north, to the capital, Damascus, in the south, and it's from there that President Bashar al-Assad's military has come.
Those days are now distant memories as the city became the heart of an anti-government uprising and this week became the focal point of the regime's brutal clampdown.
Rebels and civilians holed up in the besieged city are dying under a relentless barrage of rocket fire.
The Syrian military has surrounded it with tanks and heavy weapons, and snipers are positioned on roofs, picking off anyone who dares to walk the streets, opposition activists say.
They fear that now, after a brutal week-long assault, the army could be about to move in to wipe out the resistance.
No one knows for sure how many people are living under the barrage. They cower in their homes as shells explode, destroying buildings and killing indiscriminately.
The death toll is rising daily as world leaders talk, but with powerhouses China and Russia so far siding with Syria, there has been little more than rhetorical support.
One man, who has got the message from Homs out to the wider world via YouTube and CNN, is 'Danny' -- an assumed name to protect his identity.
Pain etched across his young face, Danny said: "They are going to kill us all and if you don't help us, they'll kill millions and no one will find out about it. Please, someone help us."
After the failure last week by the U.N. Security Council to agree on a resolution condemning the violence, Homs has seen some of the fiercest attacks yet by Assad's army.
One resident, who called himself Aslan said Wednesday: "There is helicopter now that attack Baba Amr area.
"Thirty minute ago, two helicopters. Too much shooting before. And explosions in some homes there.
"In my room, beside with my friend, because my family [left the area, they are too scared] No electricity. No [internet] network. No anything. We have Thuraya [a hand-held satellite phone]. Also Lebanese [cell phone] network.
"No medicine, need oxygen now [for hospitals]."
At a hospital in Baba Amr on Thursday the dead and the injured were arriving around the clock. Ali, a doctor, said: "All I have is gauze, bandages, old stitches and (a) few antiseptic wipes."
He has no surgical equipment to help the wounded. As he spoke to CNN by telephone there were seven thundering explosions. He believed Syrian jets were firing on the city but he did not want to look out the window to check in case it cost him his life.
"There is now way to flee Baba Amr because all surrounding suburbs are also under attack and anything that moves is shot at," Hazoury says.
He reckons the assault has damaged 60 percent of homes in Baba Amr.
Families who did try to escape were captured by government forces and killed, said an opposition spokesman, who CNN is calling Abu Rami.
Videos purporting to show the violence in Homs appear to support the accounts of witnesses, although it is not possible to independently confirm their authenticity.
In one scene, a row of buildings painted in pink and blue pastels survived intact but on the other side of the street, bodies were pulled from the rubble of an attack and loaded onto flatbed trucks.
On another street a rocket tore a V-shape through a street wall as smoke filled the air.
Other video contains images of the wounded -- sometimes bleeding, sometimes bandaged -- and schools and homes that have been bombed.
On Wednesday, Danny spoke via Skype. Wearing headphones and locked in a white-walled room, he showed off a mortar that had landed nearby: "We are human beings, we're like animals being killed here. ... I am scared a rocket might land in this room and kill me.
"Women and children have got used to seeing blood and body parts in the street. They are really afraid.
"The Syrian army is surrounding Babr Ama with army troops and tanks and anti-aircraft. They have been bombarding us with rockets.
"There are snipers all around these buildings. Anyone who tries to come up the street will get shot. We always walk along the wall so the sniper does not see us."
In video dispatches posted on YouTube, Danny showed a military vehicle he said was captured by rebel fighters, civilians living in cramped rooms, bodies carpeting floors -- and his own growing desperation.
Survivors are trapped, dodging snipers and heavy arms fire from tanks surrounding the city, and waiting to see if the army advances.
The rebel Free Syrian Army -- containing soldiers who defected from Assad's military to join the rebels -- is unable to fight back because government forces are striking from outside the city beyond the range of their small arms, Abu Rami said.
"Who's going to resist? You can't see anything, so there is not any armed resistance in these areas," he said.
Parts of the city are without power. Sometimes the security forces shut down electricity and telecommunications networks ahead of early morning raids to root out opposition members.
"If you're in a place where they cut off the power or the phones, you know you're in trouble," Abu Rami said.
There is a shortage of everything from children's milk formula to oil for heating, and he says security forces are preventing medical aid from reaching dying citizens.
Standing in a shelled street, Danny yells into his camera: "Where's the U.N.?, where's the humanity, where is America?"
CNN's Ivan Watson, CNN Wire staff and journalist Mohamed Fadel Fahmy contributed to this report