Bev Jullien described making her daily jog along Whitehall on Tuesday morning before being met by clusters of police cars and ambulances by the Palace of Westminster at around 7.50am
Ten minutes earlier, a silver-coloured Ford Fiesta collided with several pedestrians and cyclists before crashing into a security barrier outside the Houses of Parliament.
Bev Jullien said she felt "alarmed" by what she saw and, referring to the injured, she said: "We will be holding them in our prayers at midday today.
"We will continue to pray for the victims.
"We will give thanks for the emergency services.
"I think we will continue to be vigilant.
The Bishop of London said she was praying for those injured in the crash - two of whom have been taken to hospital with non-life threatening injuries.
A man in his 20s has been arrested.
Rt Rev Sarah Mullally also praised officers, ambulance crews and firefighters who responded.
She tweeted: "Praying for all those affected by the incident in Westminster this morning.
"Thank you to our first responders and emergency services."
According to Scotland Yard, there was nobody else in the vehicle at the time of the crash and no weapons were discovered.
Eyewitness, Ewalina Ochab said: "I think it looked intentional - the car drove at speed and towards the barriers.
"I was walking on the other side [of the road].
"I heard some noise and someone screamed.
"I turned around and I saw a silver car driving very fast close to the railings, maybe even on the pavement."
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