Police have charged the son of a man killed in a bizarre and fatal crossbow shooting at a Toronto library with first-degree murder, authorities confirmed Friday.

The suspect, 24-year-old Zhou Fang of Ottawa, appeared in a Toronto court on Friday morning and was remanded in custody until Dec. 8.

Fang stared straight ahead and spoke softly when asked by the judge whether he understood the proceedings.

The victim in the shooting, 52-year-old Si Cheng, of Toronto, was shot in the back at the Main Street Library in Toronto's east end. The victim is the father of the accused.

Earlier, police had said the accused and the victim knew each other, adding that it was not a random attack.

The library was filled with afternoon patrons at the time of the attack, many of whom witnessed a man calmly enter the building and fire a crossbow.

"There were a number of people inside and a number of people have been taken to various police stations to be questioned," Const. Tony Vella said late Thursday.

A witness reportedly got the licence plate number of a vehicle leaving the scene. Fang was arrested a short time after the incident near Phenix Drive and Hollis Avenue, which is southeast of Danforth Avenue and Birchmount Road. That location is about three kilometres east of the crime scene.

There were reports that the shooter may have used pepper spray before firing the crossbow.

Paramedics pronounced the victim dead at the scene.

The man's body was removed from the library on a stretcher overnight. The arrow was still protruding from his body, which was covered with a sheet.

Crossbows are not subject to the same restrictions as guns and can typically be purchased without the license or certificates required for firearms. On its website the RCMP said only crossbows that are less than 50 centimetres in length and can be fired with one hand are prohibited.

It's not clear which type of crossbow was used in the murder.

At the time of the shooting, area resident Linus Smith was sitting in a restaurant across the street. She saw a man leave the library with something in his hand, get into a U-Haul van and drive off, she said.

"He came out of the library, he was calm, he went into the U-Haul and he drove off," she said. "He didn't speed off or anything, he just drove."

Vella said it was the first time he had been involved in a homicide investigation involving a crossbow.

"You hear about shootings with guns or knives involved, but definitely a crossbow is a unique situation," Vella said.

Toronto Public Library said the Main Street branch would remain closed on Friday. Support and counselling will be provided to staff and patrons affected by the gruesome incident.

The incident isn't the first homicide involving a crossbow in Canada. In 2007, a 26-year-old man was accused of murdering his mother with a crossbow in Quebec.