Three students have been praised for their bravery after rushing to help a female Australian National University lecturer being attacked with a baseball bat.
An 18-year-old student sprung from his seat in the statistics lecture in Canberra at about 9.15am on Friday and assaulted the lecturer with the bat.
Three other students - one male and two female - ran towards danger to save her.
Detective Superintendent Ben Cartwright would not be drawn on speculation the young, white male's violent outburst was racially motivated.
Several of the students were Asian, but the lecturer's background is unknown.
"It is too early to determine the motivation behind this alleged assault and at this stage, ACT policing have not ruled anything out," Detective Cartwright told reporters in Canberra on Friday.
"All indications at this stage are that it is an isolated incident. Everything is part of our investigation going forward."
The attacker was not known to police or intelligence agencies.
"He put up a fight, obviously, when he had the baseball bat but once it was taken off him the students were able to restrain him and campus security were able to restrain him until police arrived," Detective Cartwright said.
Those caught up in the assault have suffered serious but non-life threatening defensive injuries including broken bones, and have been taken to Canberra Hospital.
"Incredible bravery on their behalf," Detective Cartwright said.
"I believe one of the students has actually taken the baseball bat from the student with it and run away with it, and then returned later and given it to police."
Campus security staff raised the alarm after managing to restrain the student, and police arrived the on scene soon afterwards and taking the 18-year-old into custody.