The Delhi Police suspects the involvement of two more people along with the four who have already been held in the Wednesday security breach of Parliament, sources said.

All six were known to each other and were staying in a house in Gurugram, they claimed.

Amol Shinde and Neelam -- caught outside the Parliament -- and Sagar Sharma and Manoranjan D -- held inside the Lok Sabha chamber -- are in police custody. Two more, identified as Lalit and Vikram, and suspected to be their accomplices, are being looked for.

Amol Shinde and Neelam were arrested earlier in the day for protesting outside the Parliament building carrying cans that emitted a yellow and red smoke, police said.

The incident happened minutes after two people jumped into the Lok Sabha chamber from the public gallery and opened canisters that emitted a similar-coloured smoke, triggering panic among the MPs. They were identified as Sagar Sharma and Manoranjan D.

Police sources said that the four accused knew each other and had two other accomplices, who are yet to be traced.

"While four have been held, the fifth has been identified. The two suspects and the four accused stayed in a house in Gurugram and it seems that the incident was planned.

"No mobile phones have been found on the accused and police are looking for their phones," said a police source.

The incidents came on a day when the nation is observing the anniversary of the 2001 Parliament attack.

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

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