More than 4,500 cameras in Chicago public schools are being connected to police headquarters and the city's 911 center in a technological upgrade designed to improve safety. In an emergency, arriving officers also will be able to view real-time images from the cameras on screens in their squad cars. Cameras are installed at about 200 of Chicago's 650 public schools, including all high schools and some administrative buildings. Until now, they have been monitored only at the school district's central office.