It was the second such deadly fire to hit refugee encampments in eastern Lebanon amid soaring temperatures. On Sunday, a fire ripped through another settlement near the town of Qab Elias, also killing one person.
George Ketteneh, of Lebanon's Red Cross, says Tuesday's blaze erupted in the nearby Tal Sarhoun camp. Among those injured, seven were reported to be in critical condition. Lebanon's state-run National News Agency said 22 of the 185 tents in the informal settlement burned down.
An army statement said the four were transferred to a hospital for medical treatment immediately after their arrest last Friday, after an army doctor noticed their failing health. They died before they could be referred for questioning, it said.
The raid in the border town of Arsal led to the arrests of 355 Syrians, prompting Syrian activists to complain that refugees were being humiliated. Five suspects blew themselves up before they could be taken into custody during the raid.