An Ontario Provincial Police investigation into several Ottawa police officers accused of misconduct has ended with no criminal charges laid, Ottawa's police chief said.

In an email to his officers Thursday that was later shared with the media, chief Charles Bordeleau said three senior members of the police force and six other officers were cleared of wrongdoing following an investigation into a 2014 tactical training explosion.

"The decision to request the OPP to investigate was made in the interest of transparency. I now consider this matter closed," Bordeleau said in the email.

In May misconduct allegations came to light after Ottawa defence lawyer Michael Edelson sent the police chief a letter with documents accusing several officers of engaging in criminal conduct.

Sources previously told CBC News the letter alleged senior officers gave false statements to the Special Investigations Unit, a provincial oversight agency that probed the June 18, 2014, explosion in Kanata that injured five people. The allegations prompted Bordeleau to ask OPP Commissioner Vince Hawkes to open an investigation.

An explosion occurred during a training exercise at this abandoned home in Kanata on June 18, 2014, injured five emergency responders. (Louis Blouin/CBC)

None of the officers who were investigated was ever suspended or reassigned, Bordeleau wrote.

Now that the matter is closed, the chief upheld the importance of police oversight, but reminded his members that comes with "intense public scrutiny."

"It is my belief that the conclusion of this O.P.P. investigation is a reminder of the importance of not rushing to judgement," he said.

"I know that this has been a divisive issue both within our organization and in the public at a time when we should be striving to maintain the trust and confidence of the people we serve."