A £1 book sale at a town library was “sabotaged” when people filled their bags with dozens of library books.

The fill-a-bag sale at Batley library in West Yorkshire was “decimated” when people raided the shelves, taking children’s books, adult fiction, cookery books and graphic novels – as well as Lego from the library’s Lego club.

Steve McGrath, a volunteer who was managing the event, said he was ringing a bell and telling people only the books on the sale table were for sale. Posting on Facebook, he said he had lost his faith in humanity.

He wrote: “This was a book sale by the Friends of Batley Library, not Kirklees Libraries on Friday and Saturday. Friday’s sale went well but Saturday’s sale was sabotaged by misinformed Facebookers.

“Far too many people filled their bags with actual library books from the library shelves, not from the sales tables, even though I stood on the balcony, ringing a bell and constantly telling people that it was only the books on the tables that were for sale.

“The people who decimated the children’s library, adult fiction, graphic novels and cookery sections of books, have actively stolen Kirklees libraries stock.

“This was atrocious behaviour by some who, through social media, decided that all stock was available to take regardless of my continued announcements. Even arguing and quoting the internet posts saying fill a bag for a pound.

“This wasn’t a purge of books from a closing-down library, as some used it as. It was a regular book sale fundraiser, to provide Batley library events for our children and customers.

“People were even seen putting Lego from our library Lego club in their bags to take. It was like the worst of all jumble sales. I am shocked, saddened and disappointed that this has happened.”

He said the library had never said this was the case “but people took it upon themselves to help themselves”.

“This is the negative power of sharing and adding your own comments on social media. I’ve lost my faith in humanity slightly today. I try to do as much as I can for this wider community and although I have been ridiculed by work professionals for my passion, I still dedicate myself to providing positive experiences for the generations.

“I hope the ones who so passionately abused this event, will put the equal amount of passion and effort into trying to save this beautiful building, when we begin our campaign to save the Carnegie library.”

The library is located in a Grade-II listed building and was funded by the philanthropist Andrew Carnegie. It needs major repairs and may need to be moved.

A council spokesperson said it remained to be seen how many books had been taken and the library would know only when a full inventory had been done.