Clashes were reported at the main pro-democracy protest site in Central district after masked men broke through the barricades set up by protesters.
According to the BBC, about 500 masked men rushed the barricades erected by protesters in recent week.
A few people have been detained in connection with the clashes.
The police in Hong Kong, earlier this morning, had dismantled some of the protest camps in an operation to reduce traffic congestion, the report said.