The number of arrests in connection with Wednesday midnight vandalism at RG Kar Medical College and Hospital rose to 31 on Saturday, police said.

Almost all arrested people have claimed to the police that they “just went to join the march” on Wednesday night.

A “women, reclaim the night” call had brought out tens of thousands of women and many men that night.

Some people used the opportunity to ransack the medical college hospital in the centre of protests since the rape and murder of a young doctor on August 9.

The Kolkata Police has summoned seven Left leaders, including the CPM’s Minakshi Mukherjee, in connection with the cases started in three police stations related to the vandalism.

Some of the videos of the violence that have emerged have shown the alleged rioters waving white flags that look like CPM youth wing DYFI’s.

DYFI state secretary Minakshi Mukherjee said: “We do not trust the police. We have clearly stated our stand to cooperate with the police. We will respond to the notices but before that, we will talk to legal experts.”

She, however, said they were yet to receive the notices.

The police said some of the arrested were neighbours.

“My son just went to walk with the crowd. His only fault was he was photographed while he was standing next to his friend who was taking a picture on his mobile phone. Otherwise, he is a very good boy,” Gopal Mahish, father of one of the arrested youths, Soumyadip Mahish, told The Telegraph.

Soumyadip, known to his friends as Bumba, is a resident of Muraripukur Road and works for a pest control agency during the day and as a delivery boy at night, the police said.

Gopal Mahish identified his son in the photograph shared by Kolkata Police on their social media handle. Soumyadip, 22, he said, was the one wearing a red-and-white t-shirt, he said.

Sourav Dey, 23, also known as Babu, another young man arrested for the vandalism, also works for a pest control agency and doubles as an employee of a small garments shop, his neighbours said.

“Both Bumba and Babu are good boys. They went with me and my family that night. Suddenly there was chaos and I lost sight of them. I returned home around 3am on Thursday (August 15). They returned around 15 minutes later. The next morning, one of them came crying to me saying that their photographs were all over social media. Later, the police picked them up,” said Sourav’s next-door neighbour Biswajit Roy.

Sourav’s aunt Sikha Dey said he “always stayed away” from trouble. She added that they had no political affiliation.

Sourav, who has studied up to Class X, was identified as one of the alleged vandals. He is seen standing on a police barricade in one of the photographs published by Kolkata Police.

Subhadeep Kundu, 22, also known as Sunny, is a resident of Maniktala.

Neighbours said he was the “quiet type” who barely socialises with others. “We cannot imagine that he could be arrested for something like this,” said a neighbour.

Subhadeep was identified standing on a police barricade next to Sourav on the night of the incident.

All arrests till Saturday were made based on matching photographs, police said.

“If someone is picked based on pictorial evidence and claims that a certain person was present with him, the person in question is arrested only if his/her picture was captured during the violence,” said an officer.

The police commissioner told a news conference on Friday that most of the alleged vandals arrested till then had claimed to have reached the spot in “ones and twos” and not as part of an organised brigade.