Three women and one man were assaulted and sustained serious but non-life threatening injuries at the Australian National University in Canberra on Friday morning, ACT Police's detective superintendent Ben Cartwright said at an afternoon press conference.
An 18-year-old Caucasian man has been taken into custody and is yet to be charged, Det Supt Cartwright said, adding there was no ongoing threat.
The alleged attacker was in a statistics class when he stood up at the back of the room and approached the lecturer with a baseball bat, detective superintendent Cartwright said during the press conference.
Other students intervened, with one wrestling the bat from the attacker. Three students and a female lecturer were "seriously" hurt and all four are in Canberra hospital with one believed to have a broken arm.
Police were unable to provide a reason for the attack was but are "not ruling out" any motive, including a racial motive. At least "some" of the hurt students were Asian, detective superintendent Cartwright said.
The university's deputy vice-chancellor, Marnie Hughes Warrington, paid tribute to ANU's students, saying they displayed "remarkable bravery".
ANU say they will step up security for Open Day but stress it was an "isolated" incident.
