Armed police swooped on the scene moments after the vehicle collided with the barriers at 7.37 a.m, pointing their weapons at the vehicle before a male driver in his late 20s emerged.
He was detained and taken to a police station in south London where he remains in custody, the Guardian reported.
London Ambulance Service said it had taken two patients to hospital with non-life threatening injuries after cyclists and pedestrians were hit. A third patient with minor injuries was assessed at the scene. No one else was in the car and no weapons were found, the police said.
The decision to treat the incident as "terrorist" was made for several reasons, including CCTV recovered by the police showing the vehicle driving at pedestrians and civilians, outside an iconic site, which is seen as a high-profile target for terrorist attacks, reports said.
According to the BBC, witnesses said the silver Ford Fiesta, which was travelling westbound, appeared to deliberately hit members of the public as it swerved into the opposite lane.
Westminster tube station was closed and streets around Millbank, Parliament Square and Victoria Tower Gardens were cordoned off. The nearby Strutton Ground was also closed to the public.
"My thoughts are with those injured and my thanks to the emergency services for their immediate and courageous response," said Prime Minister Theresa May.
The Houses of Parliament, as it is known, are surrounded with security barriers of steel and concrete. The measures were extended after the Westminster Bridge attack in March 2017 when a Khalid Masood ploughed a car into crowds on the bridge, killing four people.
Masood abandoned his car and then stabbed and killed an unarmed police officer, Keith Palmer, before he was shot by police in a courtyard outside Parliament.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
