Saints briefly led after goals from Adam Armstrong and Mateus Fernandes cancelled out Dominik Szoboszlai’s first-half strike.
Nat Sciver-Brunt hit a half-century as England earned a four-wicket victory against South Africa in their T20 opener.
Officers were called at about 10.45am on Sunday after a fight reportedly broke out on the bridge in central London.
Rhondda Cynon Taf County Borough Council, South Wales Fire and Rescue, Natural Resources Wales and South Wales Police have declared a major incident.