In an outpouring of grief and anger, southern Sudanese set fire to cars and chased passers-by from central Khartoum on Monday after hearing of the death of their hero, who had come to the capital in triumph barely a month before to take his position in a new government.

Garang and 13 other people died Saturday when their helicopter crashed into a mountain in southern Sudan in bad weather.

His Sudan People’s Liberation Movement stressed that the crash was an accident, not foul play, and quickly named Garang’s longtime deputy, Salva Kiir Mayardit, to succeed him as head of the movement and as president of south Sudan, spokesman Yasser Arman told The Associated Press.

Kiir will also likely be first vice president, according to the January peace agreement that says whoever is SPLM leader will hold that position in the presidency, said Kenyan Gen. Lazaro Sumbeiywo, a mediator in the peace talks.

Garang’s death came exactly three weeks after his July 9 inauguration into a national unity government that was seen as the key to bringing comprehensive peace to Sudan. He was working with the president and second vice president to form a Cabinet by Aug. 9.

"Losing the brother, the doctor, is a huge loss. He is a true peace partner and he has played a big role," President Omar al-Bashir said.

Three days of national mourning have been declared.

"I feel like all my hopes are now broken," Ashraf Abdel-Hafez said, sinking his head into his hands. Three weeks ago, the 26-year-old hotel employee beamed with excitement at the promise he saw in Garang’s return to Khartoum. On Monday, he cried for Garang’s death.

Others reacted violently to the news. Hordes of young men filled downtown, smashing car windows and tearing doors off, setting fire to some, looting shops and in some cases chasing pedestrians away with stones. One group stopped a passing journalist and asked, "Are you with us or against us?" and demanded to search his briefcase before they let him pass.

"Murderers! Murderers!" yelled some protesters, alleging the Sudanese government, which had battled Garang’s rebel force for two decades before this year’s peace deals, may have been behind the crash.

There was no information immediately available on how many of those killed were security forces and protesters.

Police and soldiers used tear gas to disperse the larger crowds of SPLM supporters, and by midday downtown was practically empty. All the streets leading to the Republican Palace were sealed and many residents and shopkeepers closed their shutters and stayed indoors.

A 6 p.m. to 6 a.m. curfew was imposed and by dusk, only a few people walked the empty streets. Some stopped to stare at the empty shells of burned out cars, but most just hurried past. Outside one shop, a small group of people stood talking near a pile of canned and boxed food that had been thrown out by looters.

Government and SPLM leaders appealed for calm, saying the nation’s peace process would remain on track.

"I take this opportunity to assure the southern Sudanese in particular and the Sudanese people in general that we in the SPLM/A leadership will continue the vision and the objectives of the movement that Dr. John Garang De Mabior has articulated and hoped to implement," Kiir said in a statement.

Jan Pronk, the U.N. secretary-general’s special representative in Sudan, mourned Garang’s death but said the peace process would continue.

"The peace agreement is an agreement between two institutions - the government and the SPLM. It is not dependent on individual persons, even if individual persons have had a very important contribution to it," Pronk told reporters. "I’m fully confident that the government and the SPLM will continue on this road."

Garang was the dominant voice of the south since forming the rebel group in 1983. A former colonel in the Sudan Armed Forces, he was sent south to quell a rebellion and ended up deserting to form the SPLA, which fought the Muslim Khartoum government for a share of Sudan’s wealth and political power for the mostly Christian and animist south. More than 2 million people died in the conflict before the peace agreement was signed in January.

The deal, which promised wealth and power sharing to the south, and Garang’s ascension to the national unity government were signs of hope for others who feel marginalized in Sudan. Many in the east and west, fighting their own battles for equality with Khartoum, considered Garang an advocate who would ensure the government finally paid attention to them.

The charismatic leader was welcomed by more than a million people from all regions of Sudan when he returned to Khartoum on July 8 for the first time since his rebellion against the government began in 1983.

Senior SPLM official Deng Alor, speaking from the southern Sudanese town of New Site where Garang’s remains were taken, promised an investigation into the crash. He said weather was bad in the area where the accident occurred but said human error could have been involved. He wouldn’t rule out foul play but said his group didn’t blame the government for the accident.

Although Garang and al-Bashir were once bitter enemies, they hailed each other as brothers since the peace agreement. Other past enemies, such as leading opposition figure Hassan Turabi, also became supporters of the south, at least publicly, and even tried their own peace deals with Garang.

Garang seemed to have good relations with other leaders in the SPLM, though they sometimes differed on strategy and the final goal - Garang didn’t want secession of the south - and though there are other southern opposition groups with different priorities and methods, none were seen as a threat to his life.