Human bones have been found stuffed inside a hidden underground tunnel.
Urban explorer José Flores, who has 7.8 million followers on TikTok, made the eerie discovery while walking through a grassland with a friend.
The catacombs were littered with skeletal remains and religious artefacts.
READ MORE: Man finds secret door leading to hidden room in new home – and discovers devastating secret
And in a video which has amassed 737,700 views, he brought his social media fans along for the ride, as reported by Need To Know.
Catacombs are underground burial chambers or tunnels, often used for religious purposes, particularly by early Christians and Jews.
They are essentially subterranean cemeteries, with galleries or passages containing side recesses for tombs.
While walking through the grassland, José discovered a tombstone which looked as though it had a religious symbol spray-painted on it.
He quickly found the hidden catacombs nearby.
Piles of skeletal remains could be seen as José made his way inside.
After venturing deeper into the crypt, he was eventually able to stand up and roam around in the darkness.
Religious artefacts were also found inside the cave, including a Christian cross.
José, who is from Mexico, said in the caption: “I entered the secret catacombs of Mexico.”
His video received over 91,000 likes and more than 1,000 comments from shocked viewers.
Some said they heard the voice of what sounded like a woman at the end of the video.
One person said, “Aren’t you afraid?”
Another viewer said: “Someone heard a voice at the end of the video? I did hear something.”
“I heard a woman’s voice as the video was ending,” added Laurita.
Brian said, “In the last second of the video, someone heard a woman’s voice whispering, or is it my imagination?”
“Omg. I don’t understand how he’s not afraid, just looking at this makes my body cold with fear,” Cruz added.
READ MORE: Ghost-hunting parents dubbed ‘UK’s Addams Family’ SLAMMED for using kids to speak with the dead
