He told The Sun newspaper: "We found her on the bus and she was begging us to let her stay.
"I said to her, 'Well, you can, but you need to think really carefully about traveling with a bunch of lads.'
Then I started to see things weren't right. She started to scare the s**t out of me, to be honest. She was a big girl from Wigan and it became one of the most scary things I've seen from a fan. I had been sort of joking with her but then she wouldn't leave the bus. She just refused to go.
"Security ended up coming and literally pulled her out."
The group - who also consist of Tom Parker, Jay McGuiness, Nathan Sykes and Siva Kaneswaran - became the highest charting British boy band in the US last week when their single 'Glad You Came' reached number five on the Billboard chart.
Despite their American success, they have been mistaken for real-life versions of UK comedy TV show 'The Inbetweeners'.
Jay explained: "Americans thought we were a real-life version of 'The Inbetweeners'."
Here's their top video on YouTube: