An international student was arrested on Thursday for allegedly stabbing three people at the University of Waterloo in Ontario, Canada, authorities said. 

The suspect, 24-year-old Geovanny Villalba-Aleman, had been studying at the university and recently graduated, police said. He allegedly targeted a gender studies class during the Wednesday attack. 

"Investigators believe this was a hate-motivated incident related to gender expression and gender identity," the Waterloo Regional Police said. 

Investigators determined that the suspect was not a member of the class but spoke to the professor before allegedly attacking her with two large knives. Some students tried to stop the attacker while others fled the classroom, Waterloo police said at a press conference Thursday.

There were approximately 40 students inside the classroom when the suspect stabbed the professor, a 38-year-old female, one 20-year-old female student and one 19-year-old male student.

As the incident unfolded, the university told students in the building to shelter in place. 

"If you are in Hagey Hall, please stay in place until you are escorted out of the building by Police who are now clearing the building room by room," the university tweeted Wednesday afternoon.

At 3:37 p.m., police received multiple emergency calls from students and responded promptly. The suspect was identified based on the description students provided, and he was arrested inside the university building without incident. 

He is being charged with three counts of aggravated assault, four counts of assault with a weapon, and two counts of possession of a weapon for a dangerous purpose and mischief. 

"Yesterday's stabbings at a gender studies class at the University of Waterloo are horrifying and unacceptable," Canadian Prime Minister Justin Trudeau wrote on Twitter. "This type of violence must always be condemned."

In a statement issued Thursday, the school's provost, James W.E. Rush, called the attack "shocking."

"In the coming days many of you will have questions about why this happened and about the University's response," Rush wrote. "My commitment to you is that senior leaders will be as transparent as possible with the information we have."

In:
• Hate Crime
• Canada

S. Dev is a news editor for CBSNews.com.