Video of French Police Violently Arresting Black Woman

French police are under fire for twisting a black woman's arm and pinning her to the ground during an arrest -- a loud and horrifying incident captured on video.

The arrest reportedly went down earlier this week at a train station outside Paris when a couple of cops first shoved the woman and directed her to leave the station. Within seconds, both cops had her arm behind her, and slammed her to the ground.

The video started circulating on Twitter with the caption, "French police assault a PREGNANT black woman and put her on her belly despite her cries of pain. The French president still denies the existence police violence."

We can't confirm the woman is pregnant -- someone in the background yelled that she is -- but she was very clearly screaming in agony while on the ground. She repeatedly yelled, "pourquoi," (why, in English)

The railway authority in France reportedly said the video's being taken out of context. The agency claims the woman spat and tried boarding the train without a ticket before officers stepped in. The railway authority has now opened an internal investigation.