India's parliament was halted Wednesday after a major security breach that saw two people disrupt proceedings by setting off a smoke canister inside the legislature.
The pair were arrested by security, along with two others detained outside the building, after one man jumped onto the floor of the lower house of parliament from an overhead visitors' gallery.
Official footage from the session showed one man shouting slogans and vaulting over tables between stunned lawmakers before a device was set off that caused yellow smoke to billow into the chamber.
The motives of the pair and how they managed to evade security checks were unclear, with police in New Delhi yet to release any details on the incident.
Parliament resumed after a brief adjournment, with speaker Om Birla telling lawmakers that four people had been arrested for the disruption.
"Both persons have been arrested and two others outside have also been arrested," he said.
Birla said that the parliament was "carrying out a thorough probe and the Delhi police too had been given necessary directions".
He added that "there was nothing to worry about" and assured lawmakers that the smoke was not hazardous to human health.
Lawmaker Hanuman Beniwal said the "very serious episode" raised questions about the security of India's new parliament, inaugurated by Prime Minister Narendra Modi earlier this year.
Beniwal said around 150 lawmakers were in the chamber at the time of the incident, and demanded a thorough inquiry into what happened.
The disruption came on the 22nd anniversary of an attack on the parliament's previous home in New Delhi.
Five gunmen shot dead at least eight security personnel and a gardener in that assault, which also took place on the day of a parliamentary session.
Modi had paid tribute to the victims of that attack earlier Wednesday.
"Their courage and sacrifice in the face of danger will forever be etched in our nation's memory," he said.
