Olga is joined by a Bell 214ST and two Spanish Air Tractors, also flying in from Rhodes : EC-NNC and EC-NQC

Apparently a Mil Mi-8AMT also joined the battle from the air. Unfortunately it crashed. This can be either RA-22424 (Vertical-T Air Company) or OM-AVA (UTair Europe). I'm guessing the latter based on the crew's nationalities.

Update 15/07 : Turns out it was the 3rd Mil known to be in Greece I had no info on : ER-MHU, a Mil 8MTV-1 (s/n 95617) owned by Valan ICC from Moldova as confirmed by this press release. It saw service in Afghanistan (EX-921) and flew for the United Nations.

Update 16/07 : The Valan ICC site is off-line ("Account Suspended") but the press release also appeared on their Facebook page : Resource 3.