Three thugs thought they would have it easy ganging up a hapless young medical student. Until they met a group of crime fighting ninjas.

A report by the New South Wales said that a 27-year-old German medical student was accosted by three thugs while on his way home.

However, while the student was being kicked, punched and mugged by the assailants, a student from the nearby Ninja Senshi Ryu school saw the incident. He quickly notified his instructor and fellow students and gave chase to the suspects while still decked out in their ninja gears.

"He's called out to me, 'Sensei, someone's getting mugged on the road outside!'" ninja sensei Kaylan Soto said.

Soto added: "We started running at them, yelling and everything. These guys have turned around and seen five ninjas in black ninja uniforms running towards them. They just bolted."

The ninja instructor described the assailants as very afraid and ran very fast upon seeing them.

The police later arrested two of the thugs while a third suspect managed to escape. The police also recovered stolen items from the medical student including a mobile phone and an iPod.