Eight people were arrested in India on Saturday for the murder of a politician who championed the rights of lower-caste Indians, police said.

K. Armstrong, the state boss of the Bahujan Samaj Party (BSP), was hacked to death with machetes and sickles near his home in the southern city of Chennai on Friday night.

Six men travelling on motorbikes attacked Armstrong while he was "chatting with friends and supporters" near his home in the Tamil Nadu state capital, the Indian Express newspaper reported.

The men reportedly escaped before anyone could intervene.

Several of Armstrong's supporters took to the streets later in the evening to protest his assassination and demand justice.

Senior Chennai police officer Asra Garg said eight suspects were being interrogated after a "preliminary investigation".

Mayawati, the national head of Armstrong's BSP, who uses one name, said the attack was "highly deplorable and condemnable".

"The state government must punish the guilty," she said in a post on social media platform X.

Tamil Nadu Chief Minister M.K. Stalin also urged police to speedily conclude the investigation.

"Armstrong's assassination is shocking and deeply saddening," he said.