(CNN) -- Civilians are in hiding in the Yemeni capital as protesters and government forces struggle for control on the streets of Sanaa.
Residents in Sanaa are stranded in their homes, and some even fear looking out of their windows as they are left to wonder how long the violence will rage around them.
"We can't leave our houses to get food for our children. As soon as we walk on the street we are shot," says Rami al-Shaibani, a Sanaa resident.
Thousands protested in Sanaa's Change Square last week, but this week the square has been quiet, except for groups of youths carrying away the dead and helping the injured. Multiple witnesses and medics said dozens were killed in a violent government crackdown that started on Sunday.
Protesters have used Change Square for a seven-month sit-in demanding the resignation of President Ali Abdullah Saleh. He is recuperating in Saudi Arabia from a attack in June on his palace but has vowed to return to Yemen to finish his term.
Each wounded protester was carried by six or seven others -- sometimes friends of the casualty -- and taken to the medical camp in the square. Drops of blood created trails on the ground tracing the long, bloody route to a field hospital.
At the medical camp, hundreds of young people were covered in blood and screaming from pain. Thousands more volunteered and donated blood for those in need. It seemed that not a minute passed without another injured youth entering the medical camp.
The International Committee of the Red Cross has called for calm in Yemen, which, it said, is facing an "unprecedented level of violence."
With the limited-capacity field hospital full of patients, doctors made a desperate call for volunteers to try to help save the injured.
Dozens were killed and more than 700 were wounded -- many of them by gunshots -- over the last three days in clashes with the military, according to medical staff in Change Square.
Eyewitnesses said they had seen snipers on the rooftops of buildings surrounding the square firing almost continuously.
In one incident, an ambulance carrying three injured protesters flipped over when a rocket propelled grenade hit it, killing all five on board, the medical staff added.
Abdul Rahman Barman, the executive director of a local human rights organization, said Yemeni President Ali Abdullah Saleh's regime is attacking with no limits and does not differentiate between civilians, protesters or gunmen.
The Yemeni government has repeatedly denied accusations of excessive use of force, and said the government is committed to establishing a peaceful transfer of power. Yemeni officials have said forces cracked down on those committing acts of violence during protests. Vice President Abdu Rabu Hadi has called for a cease-fire from all sides, state-run Saba news agency reported.