From the BBC.....
What we know so far A policeman has been stabbed and his attacker shot by officers at the House of Parliament
Police are treating it as a "terrorist incident"
The attacker is reported to have mowed down several pedestrians as he drove a grey Hyundai car across Westminster Bridge before crashing it into railings
He is then reported to have run through the gates of the Palace of Westminster and stabbed the officer
Eyewitnesses said he was shot by police as he approached a second officer clutching his knife
House of Commons and Lords in lockdown - as is nearby St Thomas's hospital
Public urged to avoid the area and Westminster Underground station is closed
Prime Minister Theresa May was seen being ushered into a silver Jaguar in the grounds of the Palace of Westminster as what sounded like gunfire rang out at around 14:45 GMT
A Downing Street source confirmed the prime minster was "OK".
http://www.bbc.com/news/live/uk-39355505