Police in India's financial hub were on alert on Wednesday as hundreds of thousands of low-caste Hindus marked the 50th death anniversary of their leader, days after violent protests over the desecration of his statue.

Officials in Mumbai said they expected vast crowds to throng a park in the center of the city over the next two days to commemorate the death of Bhimrao Ramji Ambedkar, who authored India's constitution, which prohibits caste-based discrimination.

Riot police, commandos and rapid reaction forces were on standby, officials said, in case of violence. "We have deployed extra forces in Mumbai, and we are carefully monitoring the trains," said Director General of Police P.S. Pasricha.

Last week, three people were killed in western Maharashtra, of which Mumbai is the capital, as thousands of low-caste Hindus -- known as Dalits -- attacked police, torched trains and burnt buses after the alleged desecration of an Ambedkar statue in the northern state of Uttar Pradesh.

Fresh violence over the issue broke out on Wednesday in the southern state of Karnataka which shares a border with Maharashtra.

Police said they fired tear gas shells to disperse a rioting mob of low-caste Hindus that set fire to two buses and stoned several vehicles in Bidar, about 735 km (450 miles) north of state capital, Bangalore.

"Shops and offices were forced to close. Several buses have been damaged in stone-throwing incidents," Roopa Diwakar, Bidar's police chief, said by phone.

In Mumbai, a bustling city of 17 million people, traffic was thin as schools, colleges and many private offices remained closed with local residents fearing a repeat of last week.

"People are being cautious today and staying at home because of the recent Dalit outrage," said Arup Patnaik, another senior Mumbai police officer.

The Dalit community has in recent weeks been further enraged over the brutal murder of four low-caste people who had opposed the construction of a road by members of the upper-castes through their land in eastern Maharashtra.

Low-caste Hindus make up about 16 percent of India's 1.1 billion population, and have traditionally been at the bottom of the 3,000-year-old Hindu caste hierarchy.