New Delhi | In a major security breach on the anniversary of the deadly 2001 Parliament terror attack, two people on Wednesday jumped into the Lok Sabha chamber from the visitors' gallery, shouted slogans and released yellow smoke from canisters that triggered panic and chaos in the House.

Around the same time, two others, including a woman, raised slogans and released yellow smoke from canisters outside the Parliament premises, prompting the police to get into action and round up the duo.

The Ministry of Home Affairs ordered a probe into the incident following a request from the Lok Sabha Secretariat, officials said.

The inquiry committee, headed by Central Reserve Police Force (CRPF) Director General Anish Dayal Singh, along with members from other security agencies and experts, will find out the lapses in the security of Parliament and recommend action, an MHA spokesperson said.

Police sources said the security breach was a "well-planned and well-coordinated" incident carried out by six people, all of whom were in contact with each other over social media platforms.

The incident in the Lok Sabha chamber took place at around 1:01 pm when BJP member Khagen Murmu was raising an issue during Zero Hour. While one started crossing the benches in a bid to approach the Speaker's chair, the other was seen dangling from the railing of the visitor's gallery before jumping into the chamber, according to several MPs present in the House.

Alarmed members, including Hanuman Beniwal, Malook Nagar and Gurjeet Singh Aujla, overpowered and thrashed the intruders, who had come to the gallery with visitor passes facilitated by two-term Lok Sabha member from Mysuru Prathap Simha of BJP, before handing them over to the security personnel.

Defence Minister Rajnath Singh, Parliamentary Affairs Minister Pralhad Joshi, Law Minister Arjun Ram Meghwal and several opposition leaders including Rahul Gandhi and Adhir Ranjan Chowdhury were among the over 100 lawmakers present at the time of the incident.

Prime Minister Narendra Modi and Home Minister Amit Shah were not in the House as they were away in Bhopal for the swearing-in ceremony of Chief Minister Mohan Yadav.

Rajendra Agrawal, who was in the chair, adjourned the proceedings immediately for one hour.

Opposition members termed the security breach as the worst since the 2001 terror attack in which 14 persons, including five terrorists who stormed Parliament complex, were killed. They also demanded a statement from Home Minister Shah on the breach.

Trinamool Congress leader Sudip Bandyopadhyay called the security breach the worst since Independence as the attackers had managed to reach the Lok Sabha chamber with smoke canisters which could have been lethal.

Several opposition members sought to link the incident to the threats issued by Khalistani terrorist Gurpatwant Singh Pannun, to attack Parliament on or before December 13, the anniversary of the terror attack.

As the proceedings resumed at 2 pm, Lok Sabha Speaker Om Birla said a comprehensive security review of Parliament House would be carried out and at the same time made it clear that the preliminary inquiry did not indicate any links to Pannun.

Lok Sabha officials said the issuance of passes for the visitors' gallery in the

Parliament House has been suspended with immediate effect.

The Lok Sabha Secretariat has also written to the Union home ministry, seeking a review of the security measures at the Parliament building.

Top police officers including Commissioner Sanjay Arora rushed to Parliament House after the incident.

All four persons Sagar Sharma (26) and Manoranjan D (34), who jumped into the Lok Sabha chamber, and Amol Shinde (25) and Neelam (42) who were nabbed outside Parliament premises were detained at Parliament Street Police Station for questioning. Police have also detained a fifth person from Gurugram.

Sharma is a resident of Lucknow, Manoranjan hails from Mysuru, Shinde from Latur and Neelam from Hisar. Police sources said all four were staying together at a Gurugram house and they had two more accomplices.

After opening the gas canisters that emitted the smoke outside the Parliament building, Shinde and Neelam also raised slogans such as "Tanashahi Nahi Chalegi" (dictatorship will not be allowed), "Bharat Mata Ki Jai" and "Jai Bheem, Jai Bharat", police officials said.

Neelam claimed that she was not part of any organisation and was a student who was unemployed. She said she was protesting against alleged injustice against farmers, small traders and marginalised.

Later, the Lok Sabha Speaker chaired an all-party meeting where opposition members sought immediate tightening of security measures at Parliament and questioning of BJP member Simha, a former journalist and author of Modi's biography.

Facing flak, Simha's office said Parliamentarians generally entertain requests for visitors' gallery passes from members of their constituency to witness Parliamentary proceedings.

According to the Parliament rulebook, the MP has to certify that the "visitor is my relation/personal friend/known to me personally and I take full responsibility for her/him".

A large number of visitors have been coming to the new Parliament building ever since it began hosting sessions in September.

Members who overpowered the two persons inside the Lok Sabha chamber said,"one of them was saying I am a patriot and came here to protest."

Many Lok Sabha members beat up the intruders before handing them over to security.

JD(U) member Ramprit Mandal said the intruders had hidden the gas canisters in their shoes and sprayed yellow-coloured gas in the Lok Sabha chamber.

Mandal, who was near the intruder, said RLP member Hanuman Beniwal and other members overpowered the person.

"One of the two was raising slogans 'Tanashahi nahi chalegi'," Mandal said.

"Suddenly there was a commotion in the House. One person was seen jumping from one bench to another. It was a very tense moment, anything could have happened. I thought, what if he has a bomb or fire equipment in his pocket? It is a serious security lapse," Sudip Bandyopadhyay, Trinamool Lok Sabha leader, said.

"Two people jumped from the public gallery, there was smoke and everyone ran. They have been caught by some MPs and security personnel. One of them is Sagar. He was the guest of Mysuru member Prathap Simha," Lok Sabha member Danish Ali said.

"It is a big security lapse. It is the anniversary of the Parliament attack. This is a matter for probe," said Ali.

Congress member Karti Chidambaram said the two persons pulled out canisters that were emitting yellow smoke. "The smoke could have been poisonous. It is a serious security breach," he added.

"They started advancing and rushing towards the well of the house and they lit up smoke sticks. Security was compromised," DMK member D N V Senthil Kumar said on X.

"Certainly, there is a loophole. At first, I thought a person might have fallen but when the second person started coming down, all of us became cautious," BJP member Rajendra Agrawal said.

"Home Minister Amit Shah gives big speeches but can't maintain security in Parliament, he must resign," TMC MP Kalyan Banerjee said.

In a post on X, Congress leader Gaurav Gogoi said, "Saw two young men unleash foul smelling yellow coloured gas from canisters inside Parliament gallery. MPs rushed to grab these men. One person was raising some slogans. This raises serious questions on another aspect of the new Parliament building- security." Security has been beefed up in the area following the incident.

Terrorists of the Pakistan-based Lashkar-e-Taiba and Jaish-e-Mohammed outfits attacked the Parliament complex on this day in 2001, killing nine people.

Meanwhile, Devaraje Gowda, father of Manoranjan, said hang my son if he has done something wrong but maintained that his son was a "good boy."

"My son is a good boy. He is honest and truthful. His only desire is to do good for the society and sacrifice for the society. He used to read Swami Vivekananda's books. I think he developed such thoughts after reading these books," Gowda told reporters.

"It is difficult to understand what was running through his mind. My son completed his BE (Bachelor in Engineering) in 2016 and was looking after the farm. He also worked in some firms in Delhi and Bengaluru," he added.