There were over 600 homicides in Chicago last year, mostly shootings

More than a million dollars a week is being spent by Chicago schools in an attempt to improve security.

Extra security guards and more metal detectors and x-ray machines are being provided to help keep guns and violence out of the third-largest state school system in the United States.

"We spend about $60m a year on security for our schools. That's the price we're paying for our society's appalling fascination with, and easy access to, guns," said Arne Duncan, chief executive of Chicago Public Schools.

"We need to be able to spend more money in the classroom and less money looking for guns."

We need to be able to spend more money in the classroom and less money looking for guns Arne Duncan, Chicago Public Schools

The safety upgrade, in place for the new term on Tuesday, is in response to a "security audit" commissioned at the beginning of the year after a series of shootings near to schools.

This safety overhaul has included re-locating school entrances, extra training for guards, more video surveillance systems and random metal detector operations.

Murder rates

The extra 36 x-ray machines will be able to check the contents of backpacks or school bags - with the aim of keeping out weapons. In the last two years in the city's schools, over 40 firearms have been detected.

The security audit also commended the effectiveness of the city's police department, which has a dedicated schools patrol.

The need for tough school security is suggested in Chicago's homicide statistics. While last year there were, on average, more than a dozen murders a week in the city, there were no students killed within school.

A large majority of murders in the city are shootings - and gang-related disputes are the most common cause of such shootings.