No serious injuries have been reported as London's terrorism police unit investigates a crash at the scene of a previous attack in England's capital.
Behind the rapid response is years of training and lessons learnt from attacks in other major cities.
Revellers shouted and threw barstools at the three attackers, who killed seven and injured 49.
The attackers ploughed a van into pedestrians on London Bridge before running into Borough Market with knives and stabbing people at random.
One person was hit with a stray bullet and is being treated at hospital along with more than 40 other people injured in a knife and van attack in London Bridge and Borough Market.
What if a Tunisia-type attack hit Europe's biggest city? Secret preparations have been years in the planning.