Installations were temporarily switched off and Kings Cross Station was evacuated because of overcrowding at the Lumiere London Festival.
Visitors to the free event on Saturday were told to check social media before visiting on Sunday evening.
The organiser, Artichoke, and the Met Police sent tweets on Saturday asking people to come on Sunday instead.
It is the first time the festival of lights, featuring installations from 30 artists, has been held in London.
'We couldn't move'
BBC reporter Fiona McKinnon became trapped in a crowd at King's Boulevard at around 20:00 GMT on Saturday night.
She said: "It was scary and potentially very dangerous.
"We couldn't move for over half an hour and saw no lights to boot. There was no help offered to us and a clear lack of marshalling."
Helen Marriage, event organiser for Lumiere London, said it had been "very, very busy" on Saturday night, particularly around Kings Cross and Piccadilly Circus.
She said; "We work very closely with our crowd management experts and the Met and our contingency plans were put into place when the crowd got larger."
She said she was "delighted" that so many people had come to the event.
The illuminated art has been placed in locations around the city including Piccadilly, Mayfair, King's Cross, Trafalgar Square and Westminster.
It was lit up for a second night from 18:30 GMT to 22:30.
Advice on the festival will be tweeted using the hashtag #LumiereLDN.