Barry Williams, a BBC member of staff based at Millbank, said: “I heard lots of screams and turned round.
“The car went onto the wrong side of the road to where cyclists were waiting at lights and ploughed into them.
“Then it swerved back across the road and accelerated as fast as possible and hit the barrier at full pelt.
“It was a small silver car and he hit it at such speed the car actually lifted off the ground and bounced.
“Then the police just jumped. Two officers managed to leap over the security barriers and then the armed police vehicles all sped towards the scene.”
Please subscribe HERE http://bit.ly/1rbfUog