Anti-regime protesters pray in the Yemeni city of Ibb on September 16, 2011 against President Ali Abdullah Saleh's rule.

Story highlights

NEW: A Gulf Cooperation Council envoy leaves Yemen with no deal on power transfer

30 of more than 80 people reported killed in clashes with government forces are buried

Five more people are shot dead by government forces in Sanaa, medical sources say

The Red Cross and Amnesty International plead for calm

CNN  — 

Opposition forces mourned their dead Wednesday, as 30 of the 83 protesters medical sources say were killed this week by government forces were buried.

Senior members of the opposition were among more than 500,000 opposition supporters to attend the funerals, witnesses said.

Five more protesters were killed by government forces Wednesday in Change Square in the capital, Sanaa, a medical team in the square said.

One died in a rocket explosion, the medical team said, and the other four were shot by snipers, according to at least seven eyewitnesses. Nine others were injured, the medical team said.

The renewed violence, with clashes reported in half a dozen different areas of Sanaa, comes less than 12 hours after a call from the country’s Vice President Abdu Rabu Hadi for a cease-fire from all sides.

At least five rockets exploded near the entrance to Change Square at 2 p.m. local time, witnesses said.

The base of defected Gen. Ali Mohsen is under heavy bombardment, with smoke in the air and fires visible inside the compound after an ongoing attack lasting more than an hour.

Mohsen defected from the Yemeni military in March and since then has joined protesters demanding an end to the decades-long rule of President Ali Abdullah Saleh.

Wednesday’s deaths follow those of more than 80 people in clashes from Sunday to Tuesday, according to medical officials.

The uptick in violence has led to increased pressure on Yemen from the international community.

Officials from the United Nations and the Gulf Cooperation Council (GCC) arrived in Sanaa Monday, hoping to help organize a peaceful handover of power.

But GCC Secretary General Abdul Latif al-Zayyani left the country Wednesday with no power transfer signed, according to the state-run Yemen News Agency.

The International Committee of the Red Cross has pleaded for calm in Yemen, which is facing an “unprecedented level of violence,” it said Tuesday.

The ICRC is “deeply concerned” by the “significant loss of life that has occurred in the last 72 hours,” it said in a statement Tuesday.

At least 25 people were killed in clashes Tuesday, medics said. Thirty-one people were killed Monday – 28 in Sanaa and three in Taiz, according to medical officials. On Sunday, at least 26 protesters were killed and more than 550 were wounded – hundreds of them by gunshots – when security forces fired live bullets and tear gas at a massive demonstration in the city, a medic said.

Abdul Rahman Barman, the executive director of a local human rights organization, said Saleh’s regime does not differentiate between civilians, protesters or gunmen.

“All are targets for the oppressive Saleh regime,” Barman said.

Government spokesman Abdu Ganadi said that “government troops are attacking armed militants who claim to be unarmed.”

U.S. State Department spokeswoman Victoria Nuland condemned the violence and called on all those involved in it to exercise restraint.

An official with the human rights group Amnesty International said the country was on a “knife edge” and the situation could spiral into a civil war.

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.

–Journalist Hakim Almasmari contributed to this report.