Taylor Swift Fans Shocked by Baby Left on Floor During Paris Concert

Taylor Swift fans have bad blood with a fellow Swiftie who left their infant lying on the floor of the Paris arena where Taylor's performing.

The shocking photo has gone viral, for obvious reasons, after it was posted by a woman who says she was at the Friday night show at La Défense Arena ... in the standing room section, when she spotted the child.

The photo shows the baby lying on what appears to be a feathered boa or jacket as an adult - hopefully a parent or guardian -- stands over them.

Sooo ... there's the first question about just bringing an infant to such a huge concert -- more than 45,000 screaming fans -- and then there's the placement of said infant!

The woman who took the pic said the child did seem to have some sort of ear protection from the loud music and crowd noise. Her caption read, "Not to be one of those people but I would genuinely call security if I saw a baby in the pit because it is NOT safe there."

Many fans expressed their anger about the baby even being allowed into the arena. As one of them put it, "I understand sitters are hard to find, so if you really needed to bring them, you shouldn’t be in the pit. you should have a carrier for them."

Another said, "What in the actual… why. Just why. Why would you risk that?"