Right now something is going in London and no one knows exactly what. A car mowed down several pedestrians on Westminster Bridge. Parliament has been evacuated after gunshots and possible explosions. (Updates at bottom of post.)

Helicopter landing in Parliament Square pic.twitter.com/TKHJCWsUOG

— Nick Eardley (@nickeardleybbc) March 22, 2017

News Alert: Witnesses describe gunfire outside U.K. Parliament. pic.twitter.com/uq2IrhyFDT

— Fox News (@FoxNews) March 22, 2017

BREAKING: Shots, explosions heard outside of U.K. Parliament https://t.co/0Jj8ht76RL pic.twitter.com/S2RTxCuOF7

— The Daily Beast (@thedailybeast) March 22, 2017

#BREAKING: 'Two men shot by cops' outside parliament after 'car mowed down pedestrians'; 12 people injured pic.twitter.com/V1yFjlt8SQ

— Amichai Stein (@AmichaiStein1) March 22, 2017

I’m guessing this is white nationalists unhappy with the speed of Brexit. But I might be wrong.

UPDATE: BBC reports a police officer has been stabbed as well. There are two or more separate incidents. Armed officers are inside Palace of Westminster and Parliament is on lock down.

UPDATE:

BBC report just now: "At least four people lying on the ground, some bleeding heavily and apparently unconscious on Westminster Bridge."

— Caleb Howe (@CalebHowe) March 22, 2017

UPDATE: Prime Minister safe at 10 Downing, not ‘involved” in Westminster situation – officials. (BBC)

UPDATE:

London MET' SCO19 or CT-SFO operators near Westminster pic.twitter.com/cxGi57DwiH

— Harry Boone (@towersight) March 22, 2017

UPDATE:

People run out of UK parliament following major security incident in Westminster https://t.co/6WSgpTr8cz pic.twitter.com/eAt5cGmkJq

— CNN International (@cnni) March 22, 2017

UPDATE: Hospital tells BBC that one woman struck by the vehicle on the bridge has died.

#Westminster #westminsterbridge pic.twitter.com/4MYGsxqr7g

— Caleb Howe (@CalebHowe) March 22, 2017