JUBA - At least 170 people have been killed after an oil tanker exploded in South Sudan , officials say.

The tanker had veered off the road in Maridi, Western Equatoria state, and local residents were siphoning off the fuel when the vehicle exploded, they said. At least 50 people are reported to have been injured.

Local hospitals have been overwhelmed, and state officials have appealed to the Red Cross and the UN for help, BBC reported. The tanker was travelling from the capital Juba and was close to Maridi, some 250km (155 miles) away, when it came off the road and overturned.

Maradi county commissioner Wilson Thomas Yanga told the BBC’s Focus on Africa programme that while the driver went to the nearest town to get help, local residents had descended on the tanker to collect some of the petrol it contained. He said it was not yet clear what caused the explosion.

Yanga confirmed the death toll had risen to 176, and said officials feared the true number of wounded was not yet known as many may have fled the scene. Doctors and medical staff were flying in from across the country to help with the emergency, he added.

Local doctor Chandi Savior told Radio Tamazuj that they were low on supplies of basics such as oxygen and pain killers. He said many people had arrived with burns and they were “not really able to calm down this pain”.

South Sudan became an independent country in 2011, after a peace deal with Sudan that ended Africa’s longest-running civil war. But the country is one of the poorest in Africa, and more than 2.2 million people have been forced to flee their homes because of a conflict between government troops and rebel factions.

A tentative internationally-mediated peace agreement was signed in August but the ceasefire has already been violated.

Reuters adds: In addition to those killed in Wednesday’s blast, Charles Kisagna, the minister of information in Western Equatoria, said about 50 people were seriously injured.

“We don’t have medical equipment and these people may not survive because we do not have the facilities to treat the highly burnt people,” he told Reuters, adding the truck had been travelling from the capital Juba to the Western Equatoria area.

Such incidents have happened before in the east African region where fuel tankers often have to travel long distances along potholed roads and pass through poor communities.

There are almost no tarmac roads in South Sudan , one of Africa’s poorest nations, which has been mired in conflict since December 2013. Rebels and the government signed a peace deal in August, although the ceasefire has already been violated.

Presidential spokesman Ateny Wek Ateny said Wednesday’s incident was not related to the conflict. “This was an accident,” he said.

In June 2013, at least 30 people were killed and scores more injured when a broken-down fuel tanker exploded on a highway in Uganda while they were trying to siphon fuel.