The man who allegedly murdered two children at their home here knew the family and had gone there seeking money for payment to a hospital where his pregnant wife was admitted, the FIR said.

Hours after the murder on Tuesday evening, the accused Sajid (22) was gunned down in an encounter with the police, IG Bareilly range RK Singh told PTI.

The police on Wednesday detained the father and uncle of the accused.

The other accused, Sajid's brother Javed, is absconding, police said.

Sajid, who had recently opened a barber shop in the locality, allegedly attacked three brothers -- Ayush,12, Ahaan alias Honey, 8, and Yuvraj, 10, with a knife. Ayush and Ahaan died in the attack, while Yuvraj was rushed to a hospital with grievous wounds.

After the incident, Sajid's shop was set on fire. Some other shops nearby and a motorcycle were also vandalised by local people and the boys' family members.

The FIR, based on the complaint by the victims' father Vinod Kumar, said Sajid and his brother Javed reached the house at around 7 pm.

Sajid told his wife that he needed Rs 5,000 to pay the hospital for the delivery of his child.

When the wife went inside to get the money, Sajid went to the rooftop of the house. Moments later, Javed also reached the rooftop and they called Ayush and Ahaan, according to the complaint.

The accused attacked the minors with a sharp knife. When they came downstairs, Sangeeta saw that their clothes were drenched in blood.

According to the FIR, one of them said, “I have done my work today.”

The accused also attacked the third son Yuvraj who had gone upstairs to fetch some water. Yuvraj is admitted in hospital and his condition is said to be stable.

The boys' father, who is a private contractor, was out of the district at the time of the incident. Apart from his wife Sangeeta, his mother was present at the house.

Police have also not confirmed the motive behind the incident.

They have booked both Javed and Sajid for murder (under IPC Section 302 IPC).

"We have detained one Babu, the father of Sajid and Javed and their uncle Kayamuddin for questioning. The move is part of our efforts to arrest Javed who is absconding," said Budaun's Senior Superintendent of Police Alok Priyadarshi.

Nazarin, the mother of the accused, said that her sons faced the consequences of their actions.

"I don't know what was going on in their minds. They do not have any rivalry with anyone. I feel very sad for the children to whom this has been done," she told PTI Videos.

When asked about the police encounter, she added, "They faced the right consequence for their wrong actions."

Some right-wing Hindu groups staged a protest against the double murder on Wednesday morning.

Samajwadi Party leader Shivpal Singh Yadav, who is also the party's nominee for the upcoming Lok Sabha poll in Budaun, slammed the government, saying law and order has “totally failed” in the state.

"The incident in Budaun is very saddening,” he told reporters.

On the encounter during which Sajid was shot dead, he said, "I congratulate the district and police administration for the action but the truth behind the incident must also come out."

The last rites of the two boys were performed after a post-mortem examination in the morning. There was heavy police presence at Kachchla Ghat during the rites, officials said.