At least three people have been killed in protests by low-caste Hindus across India's Maharashtra state, police say.
At least two trains were set alight by protesters
One person died when police opened fire on protesters. Crowds attacked property and set fire to at least two trains on the outskirts of Mumbai (Bombay).
More than 50 people, 30 of them police, were hurt in the protests and nearly 100 vehicles damaged, police say.
Unrest began after a statue to BR Ambedkar, a low-caste hero, was destroyed in Uttar Pradesh.
Ambedkar, the chief architect of India's constitution, came from Maharashtra in the west of India. A low caste Hindu, or Dalit, he later converted to Buddhism. Dalits account for nearly 13% of the state's population.
Police in Uttar Pradesh state in the north say a number of people are being questioned in connection with the destruction of the statue in the city of Kanpur on Tuesday night.
The old statue was buried with full honours to try to head off protests and quickly replaced with a new one. Kanpur and other areas in Uttar Pradesh remain peaceful, police say.
Maharashtra police chief DS Pasricha told reporters in Mumbai that the three Dalit protesters had been killed in violence during state-wide demonstrations since Wednesday.
The man killed by police was shot during unrest in Usmanabad district.
Injuries to police personnel and about 20 protesters had been sustained in "various incidents" across the state, Mr Pasricha said.
"Buses and trains have been damaged in stone-throwing and arson. But the situation is now under control," Mr Pasricha said, the Associated Press reported.
Earlier, he told the BBC that three people had been arrested in connection with the killing of a Dalit on Wednesday.
About 1,500 people had been detained by the authorities to try to prevent violence, he said.
Rail officials say at least two empty trains were set alight by protesters in the Ulhasnagar suburb of Mumbai.
Last month, widespread Dalit protests broke out in Maharashtra's Vidarbha region following the killing of four members of a Dalit family.
The family were killed because they refused to allow upper-caste Hindus to build a road over their land, it is alleged.