At least one child has died after a big fire engulfed a camp for hundreds of Syrian refugees in Lebanon's Bekaa Valley according to aid workers, who believe that there may be two more victims.

Flames and thick clouds of black smoke rose on Sunday from the site near the town of Qab Elias, which is an hour's drive from the capital, Beirut, while exploding gas canisters could be heard from a distance.

The blaze, which destroyed about 100 tents, also left at least six people injured according to the Red Cross. Emergency workers said the fire had turned the tent camp into "ashes", with only the bathrooms at the edge of the settlement left standing.

Al Jazeera's Imtiaz Tyab, reporting from the scene, described scenes of "utter devastation".

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"This is really quite shocking for refugees," he said. "These are people who fled war and conflict, people who left behind their homes, and the homes they built here from bits of wood and sheets of plastic have been reduced to ashes."

"First responders told us they believe this fire was started by some sort of cooking accident," Tyab continued.

"They believe one of the residents of this camp had been cooking food inside their home and that it had somehow caught fire."

The fire spread rapidly and all that is left is smouldering ruins, he added.

"These Syrian refugees, who already fled their homes from the fighting, had very little to begin with - but now they have nothing."

Large plumes of black smoke can be seen above Bekaa. Hundreds of thousands of Syrian refugees live in informal tented settlements there — Imtiaz Tyab (@ImtiazTyab) July 2, 2017

Dana Sleiman, spokesperson for the United Nations' refugee agency, UNHCR, said the fire had affected 102 families living in the camp, which was one of the approximately 3,000 informal settlements in the country.

"It's a very tragic situation," she told Al Jazeera from Beirut. "Unfortunately tented settlements of this sort - because of their informality and spontaneity as they are built in very ad hoc ways - are at high risk of fire during the summertime especially."

Sleiman said aid agencies were on site to help the families and assess the situation to gauge the damage.

"The Lebanese Red Cross has already provided a secure shelter for these families to spend the night tonight, and our teams have negotiated another piece of land for them to relocate and we will provide them with the tools they need to set up their tents again."

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Lebanon is hosting at least one million Syrian refugees officially registered with the UN, many of them living in informal tented settlements scattered around the country.

But the government says the number of Syrian refugees in Lebanon is closer to 1.5 million.

"The fact is that in Lebanon there are no formal camps, so refugees are spread ... pretty much across the country," Sleiman said.

She added that since there has been no governmental decision to build formal camps, many refugees are trying to do the best they can and find the cheapest accommodation possible.

"One solution has been to expand what formerly used to be tented settlements for seasonal workers here in the country. So these have expanded in size and in number and have spread more across the whole country, especially in the Bekaa area, which this fire happened, and also in the north," Sleiman said.