Lebanon is home to more than one million refugees fleeing the conflict in neighbouring Syria, many of whom live in informal tented settlements in the arid Bekaa Valley.
Sunday's fire broke out in a refugee camp near the village of Qab Elias.
"One person died and six were wounded. About 700 refugees were evacuated from the camp," George Kettaneh of the Lebanese Red Cross told AFP.
Residents said the victim was a child but the Red Cross did not confirm the report.
An AFP correspondent said Red Cross volunteers and firefighters were still helping wounded refugees out of the camp to receive treatment.
Residents of nearby villages could be seen using their own trucks and tractors to bring tanks of water to help extinguish the blaze.
Zafer al-Nakhlawi, a Lebanese who lives in Qab Elias, said he came to the camp to help firefighters put out the blaze.
"There are only three tents left standing out of the camp's 93 tents. Part of a nearby wheat field was also burned," Nakhlawi said.
It was unclear what caused the fire, but Nakhlawi said he suspected that scorching temperatures of 36 degrees Celsius (96.8 Fahrenheit) and the valley's whipping winds may have been a factor.
The blaze came two days after clashes in two refugee camps in Lebanon's northeast left a young girl dead and seven Lebanese soldiers wounded.
Four suicide bombers detonated explosives as the Lebanese army raided the Al-Nur camp near the border town of Arsal on Friday, the armed forces said.
The girl, whose parents are both refugees, was killed and three soldiers wounded.
A second raid on the nearby Al-Qariya camp wounded three Lebanese soldiers, the army said.
