Indian police on Thursday levelled terrorism charges against four people accused of setting off smoke cans in and around India’s lower house of Parliament, according to local media. The security breach took place on Wednesday when two of the men breached the Lok Sabha chamber from the public gallery during Zero Hour, released yellow gas from canisters and shouted slogans. Zero Hour is a period when members of Parliament raise issues that require the government’s immediate attention.

Following the attack, the Delhi Police registered a case against the suspects under sections 16 and 18 of India’s Unlawful Activities (Prevention) Act, an anti-terror law, along with other Indian Penal Code provisions related to criminal conspiracy, trespass, provoking a riot and obstructing a public servant in the discharge of functions.

Police claimed that there was a “well-planned conspiracy” behind the incident. Suspect Lalit Mohan Jha said that the group had been planning this for a long time and wanted to copy the revolutionary Bhagat Singh’s act of throwing bombs inside the Central Assembly during British rule in India. One of the suspects had shared a pamphlet with the term “Missing” all over it and a picture of Prime Minister Narendra Modi on social media.

An Indian court on Thursday remanded the suspects to Delhi Police custody for seven days.

The security breach fell on the 22nd anniversary of a deadly Jihadist attack on the premises of the Parliament in 2001.