Borders MP Calum Kerr found himself caught up in Wednesday’s attack on Westminster when four people, including a policeman, died and 40 people were injured.
Mr Kerr was walking from his London office to the House of Commons at the time and witnessed the aftermath.
Immediately after the event the Berwickshire, Roxburgh and Selkirk MP said: “I was coming across from Portcullis House [where members of parliament and their staff have their offices] as a vote had been called.
“Suddenly, there was panic and people were running towards me, shouting ‘shots fired’.
“Then, armed police started running towards me, heading towards Portcullis House.
“As a result, I headed across towards the main chamber and saw what appeared to be two bodies down in New Palace Yard, surrounded by people who looked to be treating them.
“We were ushered inside and are currently in lockdown.
“I’d like to pay tribute to the professionalism of the Parliamentary estate staff and the emergency services.”
This morning Mr Kerr added: “Today I attended a minute’s silence to remember those killed in yesterday’s attack.
“There is nothing that I can say that will fully describe the respect I feel for the courage and professionalism shown by staff on the Parliamentary estate and the emergency services — particularly those members of the Police who are charged with guarding democracy and who today are grieving for the loss of one of their number.
“My thoughts go out to the friends and loved ones of all who are now dealing with the awful outcome of this act.
“But the best way that we can pay tribute to those who have lost their lives in this mindless act of violence is to carry on with the day-to-day functioning of democracy.
“Today, the mood of calm defiance in Parliament is shared across all parties, amongst staff, MPs and security personnel.
“It has been a profoundly moving experience to see both Houses of Parliament up and running again: refusing to allow this event to change who we are or how we carry ourselves.
“As a politician who works in the heart of a city like London, in a world where events are so unpredictable, you’re acutely aware that such events might take place. But that still doesn’t prepare you for the terrible shock of witnessing the reality.
“Yesterday’s event is a deeply tragic reminder that my job — representing the voters of my constituency at Westminster — is only possible due to the work of those whose job it is to keep us all safe. We owe them a huge debt of gratitude that we can never repay.
So our offices remain open, Parliament is sitting this morning and I will be sticking to my own schedule. In doing so I feel more privileged than ever to be here speaking up for my own part of the country
That work must go on.”