The Samajwadi Party chief said proper action was not taken in connection with the killings.
Samajwadi Party President Akhilesh Yadav said here on Thursday that the killing of six persons in Deoria has exposed the "unjust working of the system" and held the BJP-led state government responsible for it.
Mr Yadav also criticised the central government over the arrest of Aam Aadmi Party MP Sanjay Singh and accused it of "misusing agencies like CBI and ED".
"BJP government and its officials are responsible for the murder of six people in Deoria," Mr Yadav said while addressing a press conference here at the end of a two-day training camp of party workers.
"The unjust working system of their officials has been exposed. The government is incapable of giving justice to the poor and stopping crime," he said.
Mr Yadav accused Chief Minister Yogi Adityanath of doing politics by meeting those injured in the brutal fight which took place between two families from different castes over land.
Six persons, including five from a family, were killed in the Eastern UP district of Deoria earlier this week.
Mr Yadav said if the officials of the Adityanath government had resolved the dispute between the families, the bloodshed would not have taken place.
The government should have taken note of the dispute and suspended all junior and senior officials responsible, but the government has not done this till now, he alleged.
Mr Yadav said that a Samajwadi Party delegation will go to Deoria seeking justice for both the families.
He also attacked the government over the menace of stray cattle and damaged roads in the state. "Bulls are roaming free on every road of the state. The potholes have not been filled even after spending thousands of crores of rupees," he alleged.
The former UP chief minister said the INDIA alliance has struck fear in the BJP camp and claimed the pact will win all seats in Uttar Pradesh in the coming general election.
He also said the BJP was confused on the issue of caste census.
Mr Yadav alleged that fake cases are being filed against SP workers in every district, including Pratapgarh.
Talking about the women's reservation bill, he said, "If BJP is in favour of women's reservation, then it should give 33 per cent seats to women wherever elections are going to be held."
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)