A Metropolitan Police spokesman added that at this early stage, it is believed the police vehicle had its 'blues and twos' in operation at the time of the collision.
The aftermath of the accident was posted on twitter by several eyewitnesses.
Two people had to be cut out of this car after it crashed with a police van in Bermondsey today. http://t.co/O28MuOrCdd
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The Tooting MP has been the frontrunner in the counting process ahead of Tory challenger Zac Goldsmith.
It's not just London where elections have been taking place today. There were council elections taking place across the home counties.
A list of results for London Mayor and the London Assembly