Three men have been held over the killing of an Indian police officer in mob violence that erupted after rumours spread that cows had been slaughtered.
Subodh Kumar Singh was killed as police clashed with right wing Hindu groups who said police failed to halt the killing of cows in Uttar Pradesh state.
Cows are considered holy by India's majority Hindu population and many states have now banned cow slaughter.
The issue has sparked violence before, but an attack on police is unheard of.
So-called cow vigilantism has been on the rise and led to several killings in the past few years.
Police are now looking for 24 others suspected to be involved in Monday's murder in Bulandshahr district.
Many states have actively started enforcing bans on cow slaughter after the Hindu nationalist Bharatiya Janata Party (BJP) formed India's federal government in 2014.
In Monday's incident, a mob attacked policemen and set fire to a police station in Bulandshahr alleging cow slaughter in the area.
An 18-year-old protester was killed and another policeman was injured in the violence. BBC