Police in Canada are hunting for a suspect who dumped buckets of feces on university students in Toronto.

Late on Monday night, a female student was targeted near the University of Toronto, in the third attack in less than a week.

“A young girl had a bucket of waste – feces – dumped on her,” Constable David Hopkinson told reporters. “I don’t know what to say. I’m at a loss, this is absolutely disgusting.”

The incidents have left students shaken and wary of spending time on or around university campuses.

All of the victims are Asian students, but Toronto police believe they were selected at random.

The first incident took place on Friday afternoon, when a man wearing thick black gloves and a yellow construction helmet entered a library at the University of Toronto. The man was carrying a bucket of “liquefied fecal matter”, which he dumped on an unsuspecting student, laughing as he fled.

“It didn’t smell at first and then all of a sudden, the smell hit,” one witness told news outlet CP24. “I thought I was going to, like, faint or, like, cry … Me and my friends just packed up our stuff and ran out of the room.”

On Sunday, a man entered the library at York university and “deposited a substance, suspected of containing fecal matter, on a student”, the school said in a statement.

Police released photos of the suspect on Monday – a black male of medium build in his 30s – who they believe is the perpetrator of the previous attacks. In all three assaults, the suspect left the bucket at the scene of the crime. Police are examining the evidence, but have not yet confirmed if the substance in all three assaults was human feces.

Toronto’s police chief, Mark Saunders, called the attacks “a serious offence” and pledged the culprit would be apprehended.

The city’s mayor, John Tory, weighed in on Monday, following the third assault.

“I find this kind of behaviour inexplicable,” he said. “You just can’t understand why anybody would go around and do this kind of thing.”