The brothers, both 16, live in Isfiya, a village near where the Carmel fire began Thursday, Haaretz reported. They were taken into custody by the Central Police Unit.
The Druze practice a monotheistic religion that emerged from Islam in the Middle Ages. Druze in Israel have generally been friendly to the Jewish community and serve in the armed forces.
Authorities said Saturday the blaze, which has killed at least 42 people, might burn for days. A commander said his firefighters were dealing with flames as high as 60 feet, Ynetnews.com reported.
"At this point we have reached the best situation since the fire began," said Israel Fire and Rescue Commissioner Shimon Romach. "We are still not talking about controlling the fire. It will take us a day or two and then we'll still have the final extinguishing work, so there is a lot of work ahead."
Police spokesman Micky Rosenfeld told a news conference that 17,000 people have been evacuated. Most of the dead were police cadets brought in to help evacuate a prison who were on a bus that became trapped by the fire.
Israeli Fire Services spokesman Yoram Levy said the fire, which has burned more than 12,000 acres, could continue for a week, The Jerusalem Post reported.
"The international support that we are receiving, that is impressive, could help us to extinguish the fire Saturday night (Dec. 11)," Levy said.
In addition to 10 Israeli military aircraft dropping water and flame-retardant foam, planes from Cyprus, France, Greece, Russia and Turkey were part of the effort, fire officials said.