The Haunted Lighthouse

The lonely, isolated lighthouse on the outskirts of the coastal town, was rarely ever visited and forgotten about.
It was a eyesore, that the local townsfolk naturally assumed that it would become fully automated with AI technology.
Although there was local legends, folklore about the lighthouse being haunted, after the lighthouse keepers mysteriously disappeared without a explanation.
Sometimes there were unexplained sightings of spectral apparitions of men in lighthouse keeper attire, from a bygone era that was no longer relevant.
There was always speculation about the circumstances of what happened to the lighthouse keepers.
When the local Sheriff arrived to investigate the disappearances, the door to the lighthouse was found open, there was a trail of blood, bloody handprints smeared on the walls, broken glass, but no visible sign of the lighthouse keepers.
Their personal belongings, were left in their sleeping quarters, like they all just decided to leave and never return without any explanation, like they completely vanished from existence.
There is a rumour that one of the lighthouse keepers went insane due to the isolation, the quiet rural environment, he had cabin fever and murdered the rest of the lighthouse keepers and threw them all into the sea to hide the evidence.
The local townsfolk believed that the lighthouse keeper was possessed or influenced by a unknown evil force that couldn't be explained.
On Halloween a group of reckless teenagers that were interested in local haunted places went to the lighthouse to investigate the paranormal experiences people had.
They bought a Ouija board with them to communicate with the spirits there, while using a E.V.P device to capture disembodied voices of the lighthouse keepers.
Suddenly a dark shadow appeared in front of them and slammed the door shut, he then locked the door, axe in hand, with bloodied fingers, wearing a lighthouse keepers attire.
The teenagers were heard screaming all night at the lighthouse until they were all dead.
The local townsfolk just assumed that the teenagers were just just getting drunk and partying, so they chose to ignore what the local group of tenagers were doing.
It wasn't until the next morning that some of the townsfolk went to the lighthouse to investigate what really happened.
They were horrified when they discovered the group of teenagers dead, mutilated, covered in blood.
So what really happened to the lighthouse keepers or the teenagers?