Officers had been patrolling the River Lea towpath in Tottenham on bicycles on at 9.15pm on Wednesday and approached a group of males.
While one was arrested, two made off by bike and were chased by police also on bikes. The two suspects are understood to have entered the river at Ferry Lane a few minutes later.
One of the two males was later pulled out by officers but the second male could not be found, the Met said.
Oh, well, No loss.
The Independent Office for Police Complaints (IOPC) is now investigating how the two individuals came to be in the water and said it has taken initial statements from the officers involved.
It now wants to speak with anyone who may have witnessed or filmed any part of the incident.
So, the police do the job we actually pay them for (for once), but you want to find something to hang them with?
Commander Paul Brogden said: “I fully recognise the concern this incident will cause among members of the local community.”
If it was a real 'community', they'd be hanging out the bunting at the removal of a threat...