Eight people, 4 of them farmers, were killed in Uttar Pradesh after a violence broke out on Sunday over a visit by two ministers. This protest was held in a dramatic escalation of their 10-month long agitation over controversial new laws ahead of state polls early next year.

Here's what we know so far:

The farmers, who had joined hands to stop the visit of the Union Minister and Deputy Chief Minister Keshav Maurya, said the violence in Lakhimpur Kheri district started after their car mowed down the protesters.

"The farmers had planned to gherao the helipad to stop the arrival of the ministers. Once that ended and most people were on way back, three cars came... and mowed down the farmers... one farmer died on the spot and another in the hospital," said Dr Darshan Pal, a leader of the farmers' union, adding that the minister's son was in the car.

Also read: Priyanka Gandhi Vadra detained as Lakhimpur Kheri turns political hotspot

Union Minister of State Ajay Mishra has denied that son was linked to the violence. "My son wasn't present at the spot. There were miscreants who attacked workers with sticks and swords. Had my son been there, he wouldn't have come out alive," Mr Mishra, the junior Home Minister, was quoted as saying by news agency ANI.

"They showed black flags and pelted stones on the car, which overturned. Two farmers came under the car and died. Three BJP workers and the car driver were beaten to death by some people," he was quoted as saying by news agency Press Trust of India.

The minister also said they have video evidence of the violence. He also said that the accident was not the fault of the party workers who came to receive the ministers at the makeshift helipad.

Farmer unions said four farmers died after being hit by the car, and six others were injured.

Also read: BKU's Rakesh Tikait reaches violence-hit Lakhimpur Kheri

The farmers had assembled to block the visit of the two ministers, upset over a recent speech by Mr Mishra. Late last month, Mr Mishra had brushed off the protests against the farm laws, saying it was a protest of "10-15 people and it would take just two minutes to make them fall in line".

Chief Minister Yogi Adityanath called the incident "unfortunate". "We will investigate the reasons in detail and strict action will be taken against the accused. We appeal to all to maintain peace," he said in a statement. There is heavy police presence in Lakhimpur Kheri and internet services in the area have been stopped.

Farmer leader Naresh Tikait called an emergency meeting in Sisoli on Sunday night on further course of action. Rights activist Chandrasekhar Azad and his Bhim Army are on way to Lakhimpur Kheri.

Bengal Chief Minister Mamata Banerjee, Congress leaders Randeep Surjewala and Kapil Sibal and other opposition leaders have condemned the violence.

Congress's Priyanka Gandhi, who was on her way to meet the families of the farmers killed, was detained and not allowed to enter Lakhimpur Kheri.