Kolkata Metro authorities on Tuesday said they were investigating an alleged incident of moral policing after photographs appeared on social media showing a mob beating up a couple in a train compartment for hugging each other. However, the authorities said no one had filed a complaint about the incident yet.

The images showed a woman trying to shield a man as a group of commuters attack them with raised fists.

The couple had boarded the metro around 10 pm on Monday. After seeing the pair hugging, angry commuters objected to the “public display of affection”. An unidentified witness said that the mob shouted “get a room” and “go to a club” at the couple, NDTV reported.

When the man made a casual reply, commuters threatened the couple, saying they would resolve the matter at the train’s last stop, Dum Dum, Anand Bazaar Patrika reported.

After the train reached Dum Dum station, some commuters pushed the couple out of the train and assaulted them, before people from another compartment intervened and freed the man.

On Tuesday, residents staged a protest outside the Dumdum metro station. They held up placards against moral policing while some questioned the lack of security inside the stations.

“When I heard about this, I was stunned,” a protestor, Sayantan, told India Today. “I could instantly relate to it as I have faced similar situations myself while travelling on the Kolkata Metro. This is a clear case of moral policing with the tacit support of the police. [The] Police were completely inactive or else how could a mob pounce on a couple like that?

Writer Tasleema Nasreen also expressed her anger over the incident. “A young couple embraced in Kolkata metro,” she tweeted. “It made a bunch of frustrated old losers angry. They beat them up. Scenes of hatred are allowed. Scenes of love are considered obscene.”