Curfew has been clamped in Saidabad and Madannapet police station areas of the old city after communal trouble broke out on Sunday morning.
Police took the decision of clamping the curfew as stone pelting incidents continued unabated. One or two incidents of knifing were also reported.
Sources said three persons with knife injuries were shifted to hospital.
The RTC authorities have suspended operation of city buses to Saidabad and surrounding localities after 19 buses were damaged.
Trouble broke out following reports that a religious place was desecrated in Saidabad area in the morning.
Chief Minister Kiran Kumar Reddy and the Home Minister Sabitha Indra Reddy reviewed the law and order situation.