Although the Tutsi-dominated army insists it has pushed back the Hutu rebels who lobbed mortar rounds at the university on Tuesday, many believe the city could soon become besieged in the manner of Sarajevo or Kabul.
Yesterday, a United States aircraft landed at the airport to pick up all "non-essential" American citizens remaining in the capital. It was rumoured that the ousted Hutu president, Sylvestre Ntibantunganya, who sought US diplomatic protection shortly before a military coup at the end of July, would be evacuated on the plane.
Violence has been escalating rapidly in the tiny central African nation since the army reinstalled Pierre Buyoya, an ethnic Tutsi, as president six weeks ago today. Tutsis make up about 15 per cent of Burundi's 6 million inhabitants and Hutus 85 per cent.
The National Council for the Defence of Democracy, through its military wing, Forces for the Defence of Democracy, is fighting to overthrow the Buyoya regime which suspended parliament and all political parties on assuming power.
"The rebels are putting a lot of pressure on Bujumbura", one Western diplomat told The Independent. "There is no doubt they're better organised than they were, and that they can hurt the army if they want to. They're waging real war now".
In an effort to defuse the situation, Mr Buyoya has offered to talk to all armed groups opposing him if they guarantee to stop killing civilians. Previously, he had demanded they lay down arms before any negotiations could begin."If their purpose is to seize power," said the diplomat, "the rebels will continue to fight. If what they want is power-sharing, then they are nearly in a position to have their demands respected."
Mr Buyoya has also promised to restore the national assembly this month and to reinstate political parties within three months. These are two of the conditions regional leaders say have to be met for them to withdraw sanctions imposed on Burundi after the coup.
Fuel is now in short supply in Bujumbura as the economic blockade continues to strangle the country, and exports have been stalled. "It's difficult to tell what the reaction of neighbouring countries will be," said another Western diplomat. "Mr Buyoya's promises are a step in the right direction but they can hardly be seen [as] a sufficient answer."
Burundi's junta stands accused of massacring thousands of Hutu civilians since coming to power. Despite naming a Hutu as prime minister, Mr Buyoya has failed to win over significant numbers of Hutus.
Indeed, the largest political party, Frodebu, was yesterday reported to have thrown its support behind the rebels. Such a development would mark a significant deviation in the will of the Hutu community to resolve the conflict peacefully.
Burundi has been torn apart by ethnic strife since its first freely elected president, Melchior Ndadaye, a Hutu, was assassinated in 1993. Amnesty International estimates that more than 150,000 people have lost their lives since then.