Turns out to be a car that mounted the pavement on Westminster Bridge, plowing into people, one woman apparently dead, many injured. Same driver as the police attacker. On Sky they said there had been "explosions heard"....
I didn't say lone wolf, just that reports are he's a lone knifeman who also used his car or van as a weapon. Any motivation is still to be determined, along with any description. Terrorism is assumed as it was a deliberate attack on parliament.