The brother of the accused Bourke St killer breaks his silence with an emotional message.

The brother of the man accused of being behind the Bourke Street mall attack has broken his silence on social media to offer a heartfelt message to those affected by the tragedy.

Dimitrious ‘Jimmy’ Gargasoulas has been charged with five counts of murder after he allegedly drove his car through a crowd of pedestrians on Bourke Street, killing five people and injuring more than 35 others.

Hours before the tragedy, Dimitrious allegedly stabbed his 26-year-old brother, Angelo Gargasoulas, who has been recovering in hospital.

“To all the families of the victims involved in last Fridays tragedy, my heart goes out to you (sic),” Angelo wrote on his Facebook page.

"And for all those still fighting in hospital, my thoughts are with you and your recovery."

Angelo also wrote that "no one could've predicted what Jimmy did or that he'd do that, that morning".

"I'm fortunate enough to still have my life and the support I have received is unheard of!!! I thank everyone involved in making this an easier time for everyone else involved, and my family," he wrote.

Angelo added that he still had "some recovery time to do" after his injuries, but that it was "all looking good".

"Still in disbelief, the realism of it all has yet to fully sink in, stay strong Melbourne!" he wrote.

Four people — 10-year-old Thalia Hakin, 22-year-old Jess Mudie, 33-year-old Matthew Si, and a 25-year-old man — were killed at the scene.

Three-month-old Zachary Bryant became the fifth victim of the attack when he died in hospital the following day.