India's parliament witnessed chaotic scenes after at least two men intruded into the chamber, shouting slogans and spraying coloured gas.
Images show MPs and security officials trying to catch one of the intruders, who is seen jumping from table to table.
Reports say the men were overpowered by security officials and taken away.
The security breach occurred on the 22nd anniversary of a deadly militant attack on India's parliament.
Lawmakers said the two men jumped into the well of the house from the visitors' gallery. Their motive is not clear.
The incident occurred while lawmakers were in session in the Lok Sabha, the lower house of India's parliament. Both houses were suspended for a short period before the session resumed.
"We are investigating the matter and have asked Delhi Police to join the inquiry," Lok Sabha speaker Om Birla said. He added that according to the preliminary investigation, the smoke sprayed in the house appeared to be "harmless".
Two other people - a man and a woman - have also been detained for protesting outside the parliament by setting off canisters of coloured gas. They were pictured being led away by police.
"Two people jumped from the public gallery and there was smoke. There was chaos all around. Both of them were overpowered by security officials," lawmaker Danish Ali told reporters outside parliament.
The breach occurred on the 22nd anniversary of a deadly attack on India's parliament, in which 14 people, including five of the attackers, were killed.
Earlier in the day, President Droupadi Murmu, Prime Minister Narendra Modi and other leaders had paid tribute to the victims of the 2001 attack on parliament - 14 people, including the five attackers, were killed on the day.
Karti Chidambaram, an MP from the Congress party, said he was waiting for his turn to speak when chaos broke out.
"Suddenly, it appeared that one person had fallen down from the visitors' gallery. Then we realised that it was a deliberate act of him jumping into the well. There was another person, both of them pulled out canisters which were emitting yellow smoke," he said.
