Hundreds of Israelis sent orange balloons into the air on Monday to mark the fifth birthday of one of two children held captive by militants in the Gaza Strip. Ariel Bibas, along with his one-year-old brother Kfir, has become a symbol of the struggle to release the hostages. The orange balloons are meant to symbolise Ariel and Kfir’s bright red hair.

Among the 110 (out of 250) still held hostage, the Bibas boys are said to be the only children. Israeli authorities say more than a third of the remaining hostages are no longer alive though Israel does not consider the Bibas boys to be part of that tally.