Police said on Thursday they had arrested a 43-year-old man in Rafina, northeast of Athens, on suspicion of armed robbery.
The suspect was arrested on Tuesday night after a failed attempt to hold up a minimarket.
He opened fire on the shop after the owner locked him out.
Nobody was injured.
The suspect is also thought to have held up a mobile canteen, at which the owner and five customers were present, in nearby Artemida a day earlier.
A search of his home revealed several guns, over 1,300 bullets and shells, nine stun grenades, seven knives, four swords and two machetes.