Fifteen Indian opposition MPs were suspended after protesting a security lapse in parliament.

At least four individuals were arrested after two intruders yelled slogans and released colored smoke inside parliament. Their motivation is unknown.

The event has been investigated by the federal home ministry.

The security breach occurred on the 22nd anniversary of the parliament's tragic attack.

On Thursday, a day following the hack, security surrounding the parliament building was increased, with barriers outside the complex restricting admission.

Both chambers were postponed following opposition MPs' demands for a debate on the event and remarks from the prime minister and the home minister.

Derek O'Brien, an opposition MP, was suspended for "ignoble conduct" in the Rajya Sabha, the upper chamber of parliament, when he yelled chants demanding an explanation from Home Minister Amit Shah.

In the Lok Sabha, the lower chamber, 14 MPs from opposition parties such as the Congress and the Dravida Munnetra Kazhagam have been suspended till the session concludes on December 22.

Opposition leaders have called for punishment against Pratap Simha, a governing Bharatiya Janata Party (BJP) MP who reportedly signed the permits used by the intruders to access parliament's public gallery.

Neither Mr Simha nor his party have issued an official statement. The BBC has reached out to the MP for comment.

According to Reuters, visitor cards have been halted until a security evaluation of the parliament building is completed.

According to reports, the four accused – three males and a woman in their twenties and thirties – will appear in court on Thursday. Although police have not yet confirmed their identities, their relatives have spoken to local media, and newspapers have released their photographs and names.

The event occurred on Wednesday during a session of the Lok Sabha, the lower chamber of parliament. Earlier in the day, President Droupadi Murmu, Prime Minister Narendra Modi, and other dignitaries paid respect to the victims of the 2001 assault, which killed nine people. Security personnel killed all five of the assailants.

Two guys jumped into the parliament from the public gallery, according to MPs, and fired off canisters of colored smoke. As politicians and security personnel sought to apprehend him, one of the guys was spotted hopping from table to table.

Outside the parliament, two others, a man and a woman, chanted slogans and emitted colored smoke from canisters. The cops were seen on camera leading them away.