A man jumped into the lawmakers' area of the lower house of India's parliament on Wednesday, in a major security breach on the 22nd anniversary of a deadly attack on the complex.
TV channels showed a man wearing a black jacket jump from the visitors' area into the lawmakers' seating area, climbing over tables of lawmakers.
White and yellow coloured smoke could be seen in the chambers in a photograph posted on social media by a lawmaker and shown on India Today TV channel.
Lawmakers told TV channels that the intruder shouted some slogans they could not make out and there was a sound and some smoke.
Prime Minister Narendra Modi was not in parliament at the time.
India Today said the intruder had smoke cans hidden in his shoes and lawmakers fled the chambers as the cans released smoke.
TV channels showed the man jumping over two rows of lawmakers and trying to enter the aisles by evading security personnel. The man was later shown being taken away by police outside the building.
A woman was also shown being taken away but it was not immediately clear if she was the second person suspected to be involved in the breach.
The lower house stopped proceedings soon after the incident but resumed business about an hour later.
Speaker Om Birla told members that investigations had found that the smoke released by the man was "ordinary smoke, just to cause sensation". Two people were arrested from inside the building and two from outside the complex, he said.
Birla assured lawmakers that the incident would be investigated and a report presented to the house. He then moved on to conducting business scheduled for the day.
The incident took place in the new, high-security parliament building inaugurated by Modi in May.
In 2001, more than a dozen people, including five gunmen, were killed in an attack on the old building in the same complex, which New Delhi blames on Pakistan-based terrorists.
"I was expecting maybe they will blast something, shoot somewhere," Sudip Bandyopadhyay, a Trinamool Congress lawmaker, told the ANI news agency in which Reuters has a minority stake.
"This is a serious security lapse. How did they enter ... releasing smoke, sound," he said.
Gaurav Gogoi, another lawmaker, said one of the two suspects was shouting slogans.
"I feel there is a major flaw. There should be a proper inquiry. Lot more needs to be done," Gogoi said
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