Toronto Fire Chief Jim Sales said an internal investigation was launched after a media report in August said two firefighters had posted several sexist messages on Twitter.
Those two employees were suspended with pay, but Sales said they have now been let go along with a third firefighter after the probe discovered a "pattern" of inappropriate social media use and public comments that ran afoul of city policies.
"It is not in any way acceptable for city employees and will not be condoned by Toronto Fire Services or the City of Toronto," Sales said of the trio's actions.
"The Toronto public service fosters a corporate culture that sets the highest standard of integrity, professionalism and ethical behaviour. It is our expectation all employees demonstrate and uphold these core values," he said, reading from a prepared statement.
Sales did not divulge information about the third person fired.
The Toronto Professional Fire Fighters' Association said it is "outraged" by the firings, and vowed to fight for the reinstatement of the three firefighters.
In a toughly worded statement, the union questioned what was gained by giving the employees the boot, saying the firings fail to help the department meet its goal of a "diverse and welcoming" workplace.
"These terminations neither address the specific issues that have been raised nor do they promote the alleged objectives of the fire service."
Sales justified the firings by stating that fire service staff are in a "position of public trust."
"This trust is paramount to the division's ability to carry out its work and deliver critical services to all Toronto residents."
Union spokesman Frank Ramagnano suggested last month the two firefighters' tweets may have been taken out of context, with the posts possibly referring to quotes lifted from a television show.
He said then that the association hasn't seen any systemic issues related to sexism against female firefighters.
Two of the firefighters who have now been removed from their jobs had been identified as Matt Bowman and Lawaun Edwards.
Sales earlier said he was made aware of the tweets from reports in the media. The National Post first reported the controversial tweets in a story published Aug. 10.
The report said one tweet read: "Reject a woman and she will never let it go. One of the many defects of their kind. Also weak arms."
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