Updated

About 500 cameras installed in New York City's busiest transit hubs are now feeding real-time images to the NYPD's security network.

The transit cameras installed in Pennsylvania Station, Times Square and Grand Central station will be used to search for suspicious activity and prevent terrorist attacks as well as subway crime.

Mayor Michael Bloomberg said Monday the cameras provide the police department with better tools to keep transit riders safe.

The latest feeds are part of the NYPD's lower and midtown Manhattan security initiatives. The network of public and private cameras will eventually grow to about 3,000. Police monitor the feeds at the headquarters located near Wall Street.