In an apology letter to a disabled woman he shoved to the ground, a Vancouver police officer wrote that he believed she was reaching for his gun.

Const. Taylor Robinson wrote the letter to 26-year-old Sandy Davidsen, who suffers from cerebral palsy, after he pushed her to the ground on June 9. Neither he nor the two officers with him did anything to help her up from the sidewalk.

"The reason that I used the amount of force in which I did against you, was because I thought at the time that you were attempting to reach for my firearm," Robinson wrote in the undated letter.

"The actions that I took were purely instinctual when I felt my firearm was being targeted."

But the constable also expressed regret for his actions.

"The force in itself is something that I regret using, but it is what I did afterwards that makes me most sorrowful," he said.

"In hindsight, I wish that I would not have walked away from you, but rather helped you back up to your feet. I wish I had asked if you needed any medical assistance, if you needed help getting home."

The shoving incident in front of the Lux Hotel on East Hastings Street was caught on surveillance video, which was distributed on Thursday by the BC Civil Liberties Association.

A statement released to media by the Vancouver Police Department Thursday said Robinson reported the incident to his supervisor several hours after it happened. His actions, and why no one helped Davidsen, are now the subject of a probe by the force's Professional Standards Section.

Watch CTV News at Six for a full report from Leah Hendry

Complete text of Robinson's letter

Ms. Sandra Davidsen

I am writing you this letter for two reasons. Firstly, I would like to explain to you the actions that I made, and secondly I would like to apologize for those that I did not make.

In the day-to-day life of a police officer, we are forced to deal with multiple situations that can range from a friendly conversation to one where either our lives or the lives of others are in danger. It is because of this that I must constantly be at an elevated level of attentiveness and self awareness; this includes having control of myself and the environment around me.

The reason that I used the amount of force in which I did against you, was because I thought at the time that you were attempting to reach for my firearm. As police officers we go through rigorous training when dealing with our firearms. The actions that I took were purely instinctual when I felt my firearm was being targeted. The force in itself is something that I regret using, but it is what I did afterwards that makes me most sorrowful.

I am supposed to act as a servant to the public and I always have the public's best interest in mind. Regrettably, the way I acted that day did not represent that. In hindsight, I wish that I would not have walked away from you, but rather helped you back up to your feet. I wish I had asked if you needed any medical assistance, if you needed help getting home. Unfortunately, I have to live with the fact that I did not and I now have to take responsibility for my actions.

I am not going to try to make excuses for what I did, because all attempts would fall short. I made a mistake, and if it were possible to go back and do it over again, I would not have walked away from you while you were lying there. I would have been the one helping you to your feet and explaining to you then what had happened.

So now I would like to take this opportunity to apologize for the actions that I did not take. You did not deserve to be treated that way by not only me, but by anyone. I know that this apology is not going to make what happened go away, and I realize that the way you were treated will never be made up by any apology I can offer. Rather, I wanted to say this because it is the right thing to do. I may not have made the right decision the first time we dealt with each other, but hopefully this will be the start of only positive decisions to come.

Yours truly,

Cst. Taylor Robinson