Thousands of farmers protesting at agriculture reforms have fought through police barricades and tear gas to enter Delhi's historic Red Fort complex.
They were on foot and in tractors - part of a huge rally that was planned to coincide with India's Republic Day.
Many protesters diverted from agreed routes and clashes broke out with police. One protester has died.
Mobile internet services have been suspended in parts of Delhi as security forces scramble to restore order.
The government is yet to comment on the violence, but reports say Home Minister Amit Shah held a meeting with Delhi police to discuss the situation.
The government says the reforms that spurred the protests will liberalise the agriculture sector, but farmers say they will lose income.
Tens of thousands of them have been striking on the outskirts of Delhi since November, demanding the laws be repealed. They rejected a government offer to put the laws on hold last week.
This is one of the longest farmers-led protests India has ever seen, pitting the community against Indian Prime Minister Narendra Modi and his Bharatiya Janata Party-led (BJP) government.-BBC
