Police shot dead an aide of gangster Vikas Dubey, arrested six other alleged accomplices and sent two of their own men behind bars in connection with the ambush which killed eight police personnel last week, officials said Wednesday.
But the gangster appeared to have given police the slip in Haryana's Faridabad, near Delhi.
A team raided a house around midnight Tuesday in Faridabad's Kheli Pul area, where the gangster had stayed for a while, Haryana police said.
They arrested three people there after a brief exchange of fire.
Also, CCTV footage showed a man who resembled the gangster at a Faridabad hotel. He did not check in when a staff member insisted on an identity card with a clear photograph.
Apart from the Faridabad encounter, police engaged Dubey's alleged accomplices in Uttar Pradesh's Hamirpur, where an one man was killed, and in Kanpur, where three were arrested.
An inspector and constable were injured in the Hamirpur encounter.
The Uttar Pradesh Special Task Force (STF) also detained Dubey's brother-in-law in Madhya Pradesh's Shahdol district on Wednesday.
On Monday, the relative's son was detained.
Those arrested on Wednesday included two suspended sub inspectors, Chaubeypur station officer Vinay Tiwari and Bikru beat in-charge K K Sharma.
Both are accused of tipping off Vikas Dubey, which allowed the alleged gangster to set an ambush for a police team which had gone to arrest him at his Bikru village near Kanpur.
Since the ambush early Friday, three alleged accomplices of the gangster have been killed and 10 arrested, in addition to the two policemen.
All 68 personnel at the Chaubeypur police station, where Tiwari was the station officer, were sent to the reserve police lines.
Police sources said Amar Dubey, the man killed in Hamirpur's Maudaha village, travelled with the gangster wherever he went, ensuring his security.
Additional Director General of Police (Law and Order) Prashant Kumar said there was a reward of Rs 50,000 for his arrest.
An unlicensed semi-automatic .32 bore pistol was seized.
"Acting on a tip-off, a team of the STF and local police surrounded Amar. He was injured in the firing and he died during treatment at a hospital," Hamirpur Superintendent of Police Shlok Kumar said.
In the encounter in Kanpur's Chaubeypur area, under which Dubey's Bikru village falls, Shyamji Bajpai, also known as Shyamu, was shot in the leg, the ADG said.
Sanjiv Dubey and Jahan Yadav were also arrested with him.
Shyamu too carried a reward of Rs 50,000 for his arrest.
In Faridabad, the local crime branch arrested three men -- Ankur, his father Shravan and Kartikey alias Prabhat.
The encounter in Hamirpur followed information extracted from one of them, according to police.
Four weapons, including two 9 mm pistols belonging to police, and 44 live cartridges were seized in Faridabad, Kumar said.
The Uttar Pradesh government has increased the reward on Vikas Dubey from Rs 2.5 lakh to Rs 5 lakh.
The FIR lodged by police after the Bikru ambush named 21 people and mentioned 50-60 others.
"The STF is tracking all those named in the FIR and wherever we get information, we are taking the help of the local police," STF Inspector General Amitabh Yash said.
"We are also trying to trace the weapons taken away from the policemen," he added.
An AK-47 and an INSAS rifle, snatched during the ambush, are yet to be recovered.
Asked about the 'delay' in arresting Dubey, the IG said he is hardened criminal and used to remaining in hiding.
"But we will surely nab him. We have started getting success."