POLICE are investigating why an ANU student struck a female lecturer and three classmates with a baseball bat, as witnesses recall the horrifying attack.

Four people were injured in the incident and the alleged attacker, who is also a student, is now in police custody. He has been described as an 18-year-old caucasian male and was “not known to police or intelligence agencies”.

ANU Deputy Vice-Chancellor Marnie Hughes-Warrington said the students showed “incredible bravery to protect the lecturer”.

“All indications are at this stage is that it is an isolated incident,” she said.

“The student stood up at the back of the classroom and approached the lecturer, and other students intervened, and that is how the injuries occurred.”

The male student entered an ANU tutorial room in the Copland Building and allegedly assaulted four students and their lecturer at around 9.15am Friday.

The students were taking a class in statistics at the time. The classroom is near the student union building.

media_camera Police leave the Copeland GO32 classroom at ANU Canberra with evidence. Picture: Ray Strange.

media_camera Police activity at Copeland GO32 classroom at ANU where the assault took place. Picture: Ray Strange

Early reports suggested the attacks were random in nature, but ANU student newspaper Woroni reported that the man “appeared to attack students of Asian appearance”.

Second year student Zhuangzhuang Niu found out about the attack through a group chat.

“I heard it was a Chinese girl who got hit in the head with a bat. It’s quite serious,” he told News Corp.

“I don’t think the attack was targeted. Most of the students in the class were Asian.”

Mr Zhuangzhuang said the campus was generally safe for students.

media_camera Asian students Zhuangzhuang Niu (left) and his friend Clark at ANU Canberra where an assault took place today Picture: Ray Strange.

Australia China Youth Association’s ANU chapter president Tony Gu didn’t want to speculate on the incident but encouraged students to seek counselling if they needed it.

ANU Students’ Association did not respond to requests for comment but notified students via Facebook that there was no threat to the safety and security of staff or students.

ACT Policing’s deputy chief police officer Ben Cartwright said the injuries sustained were “not life threatening but serious”. He also said some of the injured students were Asian.

“One of the students took the baseball bat from the student and ran away,” he said.

“The students were able to alert campus security to the incident, who restrained the attacker until police arrived.”

Two of the people injured in the attack remain at Canberra Hospital.

An ACT Health spokeswoman said the pair, a male and a female, were both stable and were receiving ongoing care for minor injuries.

The other two female patients have been discharged. The spokeswoman did not confirm whether lecturer had been one of the women discharged already.

media_camera Students pass the Copeland GO32 classroom at ANU Canberra where the incident happened. Picture: Ray Strange.

A statement from the ANU media office said that there was “no indication of motive” yet.

When asked about the attack being racially motivated, ACT Police said they had not ruled anything out and forensic investigators are at the scene.

Forensic police with two large bags of evidence have left the classroom, which remains cordoned off. Classes in the room have been cancelled for the rest of the day.

Police tape around the classroom was removed just after 2pm.

They are planning to interview a large number of witnesses.

media_camera Police activity at Copeland GO32 classroom at ANU Canberra where an assault took place. Picture: Ray Strange.

ANU student Max Claessens told News Corp Australia that his friend, who was in the classroom, described the attack as a complete surprise.

“One of the students just randomly out of the blue got up with a bat, struck out at two or three students before apparently going for the teacher,” he said.

“Obviously people were in a bit of shock so they ran out to get help before the guy, who wasn’t calming down, he was going a bit crazy to be honest, was restrained.”

Mr Claessens said no one knew what sparked the attack.

media_camera Politics student Max Claessens whose friend witnessed the assault. Picture: Ray Strange.

“It was out of the blue, nothing seemed irregular about the guy,” he said.

“He had been in the class since the beginning of the term so he wasn’t an unfamiliar person at all.”

His friend, who is Asian, said there was no indication the attack was racially motivated or targeted at any other group.

There has been a random attack on students at the ANU campus, several people injured, a man has been taken in custody #canberra pic.twitter.com/U2xGPQqOlZ — Jolene Laverty (@Jolene_Laverty) August 25, 2017

The emergency staff have been amazing, #ANU staff already offering counselling to anyone affected #canberra pic.twitter.com/zhCJ2XaJbz — Jolene Laverty (@Jolene_Laverty) August 25, 2017

But ANU students Jessica Zhao and Lucas Ni say rumours are flying around campus that the attack was targeted at Asian students.

Neither was present in the classroom near Toad Hall at the time but say the campus is generally very safe.

“I’m not sure but I heard it was Asian girls that were targeted,” Ms Zhao said.

Both are international students.

Mr Ni said the campus felt safe, even at night, and students were able to contact campus security if they had any issues.

media_camera ANU students Jessica Zhao and Lucas Ni. Picture: Claire Bickers

A distressed student told the ABC of how she saw a classmate begin to wield a baseball bat against those in the lecture room around her.

“Many people got hurt … (but) a man who was very brave helped us to stop what he was doing,” she said.

The fight unfolded in the room’s doorway, preventing students from escaping.

“Because my classmate was very hurt, I called the police,” she said.

“My tutor took his baseball bat, (and) opened the door (to) let us run …

“I was running and shouting ‘help, we need help’.”

She said there were between 10-15 people in the class at the time of the attack.

#ANU student in the classroom at time of a baseball bat attack said a man suddenly started hitting her classmates https://t.co/dv79NALdlr pic.twitter.com/qskEWFFezH — ABC News Canberra (@abcnewsCanberra) August 25, 2017

Another witness to the aftermath of the attack, student Jolene Laverty told 3AW radio host Neil Mitchell she saw the alleged attacker be arrested by police.

“I saw him get arrested, he could have been a student,” Ms Laverty said.

“He was about the right age.”

media_camera A man has been taken into custody after several people were attacked on the Canberra campus of the Australian National University. Picture: Twitter/Jolene Laverty

Ms Laverty said she was walking to a lecture when she saw students with injuries outside a classroom.

“I looked over and there were a couple of students who were bleeding,” she said.

“I saw a quite serious head injury on one man.”

Ms Laverty said she hadn’t seen a weapon but overheard security guards discussing that the offender may have used a bat.

Another witness, Alex Voung, told Yahoo 7 that he was told that a man dressed in a ‘hoodie’ attacked some students and a lecturer. The man walked out of the room immediately after the incident, Mr Voung said.

media_camera The university says those affected by this morning’s violence will be offered counselling. Picture: Twitter Picture: Twitter/Jolene Laverty

A representative from the student union NTEUACT told the media: “We are confident that ANU has taken all reasonable steps with regard to managing this incident”.

media_camera The ANU's Copland building, scene of today's baseball attack on students.

The University said its first priority was the welfare of staff and students, and counselling services were being provided to all those affected.

Police said there was no ongoing threat to public safety.

They are calling on anyone who witnessed the incident to call 131 444.

media_camera Police on the scene of the Australian National University. Picture: Twitter Picture: Jolene Laverty

Today’s attack is not the first serious incident on an Australian university campus.

In 2002, a student entered a classroom at Monash University in Melbourne, killing two and injuring five. Huan Yun Xiang had entered the economics class with six loaded handguns. As he attempted to switch guns after running out of ammunition, the injured lecturer and a student tackled him to the ground.