News broke on Tuesday that the TTC employees were fired after a four-month investigation that began in the fall and involved police.
The TTC alleges the employees falsely reported handing out provincial-offence tickets to homeless people at locations where they were not actually present.
Two of the former employees each face two counts of attempting to obstruct justice and two counts of fabricating evidence. A third faces three counts of each, and two others each face a single count of attempting to obstruct justice and fabricating evidence.
The investigation also found that three additional transit enforcement officers had committed "misconduct." They have also been fired, but are not facing criminal charges.
Byford said Wednesday the news made for "grim reading" and comes at a time when the TTC is working to rebuild its reputation.
TTC workers have made news in recent years for all the wrong reasons. In 2010 a fare collector was photographed sleeping on the job. Last fall, a TTC worker was charged with stealing from a fare box.
In the same case, two union representatives are charged with tampering with evidence to cover for the theft.
'We will pull through this' TTC boss says
In his letter, Byford said the actions of a few workers have the potential to damage the reputation of everyone who works for Canada's largest transit system.
"Our Transit Enforcement Officers are decent, hard-working and honest people who do a difficult job with a high degree of professionalism," wrote Byford. "Their task just became that much more challenging due to the actions of a few."
Byford tells staff "we will pull through this."
"Our vision to deliver a transit system that makes Toronto proud remains on track."
Byford said he will back TTC staff "to the hilt when they do the right thing," but also warned that workers whose actions hurt the TTC’s reputation will not be tolerated.
"Yesterday's developments … reinforce my position that people who recklessly and deliberately flout rules or damage our reputation will face consequences for their actions. I cannot make this point any clearer."