India’s National Human Rights Commission (NHRC) is investigating alleged extrajudicial killings in Hyderabad, the capital of the state of Telangana.

Four people accused in the rape and murder of Priyanka Reddy, a veterinarian whose killing evoked national outrage, were shot dead on Friday after what the Hyderabad police claim was an attempt to steal police officers’ guns and escape.

Human rights campaigners and groups have demanded an independent probe into the custodial deaths. “There must be an independent judicial inquiry into this, there must be accountability,” said human rights lawyer Vrinda Grover. The police have received widespread public support for what many have termed “instant justice.” Celebrations hit the streets in Hyderabad with revelers showering flower petals on police officers. Prominent citizens, including federal ministers, took to social media in support of the killings.

Extrajudicial, arbitrary or summary executions and enforced disappearances are prohibited by international law. The International Covenant on Civil and Political Rights, to which India is a party, prohibits arbitrary deprivation of life and guarantees the right to a fair trial. The UN Principles on the Effective Prevention and Investigation of Extra-legal, Arbitrary and Summary Executions stipulate, “there shall be thorough, prompt and impartial investigation of all suspected cases of extra-legal, arbitrary and summary executions, including cases where complaints by relatives or other reliable reports suggest unnatural death.”