An Ontario police trainer told an inquest Wednesday that officers aren't in a position to take a softer line when responding to incidents involving mentally disturbed individuals if they are armed with a knife.

An inquest began Tuesday into the deaths of three people who were shot by Toronto police.

Michael Eligon, Reyal Jardine-Douglas and Sylvia Klibingaitis died during interactions with police in separate incidents over the past three years. All three were experiencing mental health issues and each was holding a sharp object when shot.

Police trainer Paul Bonner, right, told the inquest about the ways that officers are trained to deal with suspects who are armed with knives. (CBC)

Paul Bonner, a trainer for Ontario police forces and a former professional kickboxer, told the inquest Wednesday that it is neither realistic, nor safe, for officers to attempt to disarm suspects holding knives.

That’s why he trains officers to put a safe distance between themselves and a suspect and then to draw their firearm.

"It’s not the size of the knife that makes the difference," Bonner said, noting that a person holding a knife "doesn’t require strength to do damage to an individual."

He suggested that someone in a state of emotional distress could be even harder to deal with.

"Maybe that person, you can't reason with them and they may be even more dangerous because of the mental state that they're in," he said.

Lawyer Peter Rosenthal, representing Eligon's family, suggested police should be trained to speak in softer tones to emotionally disturbed subjects, even if they are armed.

But Bonner said that’s not part of police training.

"If it's an edged weapon, we treat it as the highest level possible, regardless of the individual," he said.

Acting as her own counsel in the inquest, Lili Steer, Klibingaitis's sister, asked Bonner whether police could use shields or batons when dealing with such subjects. Bonner said a firearm is still the safest option for police.

As for Tasers, John Zeyen, another police trainer, told the inquest the stun guns are not always reliable when responding to potential knife attacks. Zeyen also told the inquest that armed backup is always needed.

"You can't have officers relying on this 100 per cent," Zeyen said. "This device was never intended to replace a firearm."

He was also shown the eight-page warning that Taser International provides for law enforcement agencies using their device. When asked why police should use a weapon with so many warnings, Zeyen told the inquest most of the warnings relate to issues that are low risk.

"Our research has shown that the device is generally safe to use... it has its place in policing."

The inquest is due to continue on Thursday, when a police trainer who focuses on dealing with mental-health issues is scheduled to appear.