A former member of India's parliament and his brother -- both gangsters-turned-politicians -- have been assassinated in front of media and police in an incident caught on live TV in the northern Uttar Pradesh state.

Ex-MP Atiq Ahmed was under the custody of police and was being taken for a medical checkup along with his brother, Khalid Azim, alias Ashraf, a former legislator.

At least two gunmen were seen firing from point-blank range while Ahmed was talking to reporters. The shocking footage that went viral shows shooters firing and chanting 'Jai Shri Ram' [Hail deity Ram]. The shooters were immediately caught by the policemen.

The religious slogan has been turned by Hindu extremists and lynch mobs into a war cry while attacking minority Muslims and their mosques.

Three assailants identified as Arun Maurya, Naveen Tiwari and Sonu have surrendered to police, Times Now news website reported.

Local media reported the victims were taken to Prayagraj [formerly Allahabad], the state's capital, days ago, in a case regarding the killing of a lawyer in February.

The Hindu newspaper reported that Ahmed, a former gangster-turned-politician, faced more than 100 criminal cases and was among the first Uttar Pradesh politician booked under the Gangster Act in the late 1980s.

A court in Uttar Pradesh found Ahmed and two others guilty in a kidnapping case in March and sentenced them to life in prison.

Ahmed's death occurred days after his son, Asad Ahmed, was killed in an "encounter" with police in the state.

'Failure' of law and order

Ramit Sharma, a top police official in Prayagraj told reporters three attackers posed as journalists and were arrested. He said an investigation is under way.

After the on-camera killings, several opposition party leaders have criticised the far-right Bharatiya Janata Party government in the state headed by a firebrand Hindu monk Yogi Adityanath.

"Atiq and his brother were killed while in police custody and were handcuffed. Slogans of JSR [Jai Shri Ram] were also raised," Muslim leader and member of parliament Asaduddin Owaisi wrote on Twitter.

"Their murder is a perfect example of Yogi's big failure of law & order. Those celebrating encounter-raj are equally responsible for this murder."

"In a society where murderers are celebrated, what's the use of a criminal justice system?" he said.

Akhilesh Yadav, leader of the Samajwadi Party — a regional party in Uttar Pradesh, wrote on Twitter that crime has reached its peak in the state and the morale of the criminals is high.

"When someone can be killed by firing openly amidst the security cordon of the police, then what about the safety of the general public," he said.

"Due to this, an atmosphere of fear is being created among the public, it seems that some people are deliberately creating such an atmosphere."