Police in India have arrested a man whom news reports describe as a "key accused" in the security breach that occurred in parliament.
Lalit Jha, a teacher, surrendered to police in India's capital Delhi on Thursday. He has not been produced in court yet.
Four other people who were arrested on Wednesday have been charged under a stringent anti-terror law.
They have been sent to police custody for a week.
The security breach in parliament has dominated headlines in India since Wednesday. It occurred on the 22nd anniversary of a deadly militant attack on the parliament, hours after Prime Minister Narendra Modi and others paid tribute to the victims.
Two men - identified as Manoranjan D and Sagar Sharma - entered the MPs' chamber, shouting slogans and setting off smoke. Two others - Neelam and Amol Shinde - were arrested for shouting slogans and spraying coloured gas outside the house.
The four people are in their 20s and 30s and local media have reported that they told police officials that they were unemployed and wanted to express their frustration with the government's policies.
Police have not connected the four accused with any political organisations yet.
Some news reports have described Mr Jha as the suspected "mastermind" who coordinated the security breach. He has not made any statement since the breach.
The Times of India newspaper reported that while surrendering, Mr Jha was accompanied by another man who has also been taken into custody.
On Wednesday, while seeking custody of the other four accused, Additional Public Prosecutor Atul Srivastava told a Delhi court that the protest was a "well-planned conspiracy".
The breach has also led to a political uproar - on Thursday, 14 opposition lawmakers were suspended from parliament over protests. They have been demanding a discussion on the breach and asking Mr Modi and Home Minister Amit Shah to make statements.
They have also demanded action against Pratap Simha, an MP from the governing Bharatiya Janata Party (BJP) who allegedly signed the passes used by the intruders to enter the public gallery in parliament.
Neither Mr Simha nor his party have officially commented on this. One of the accused, Manoranjan, is from Mr Simha's constituency.
