Chicago police are trying to combat the city's homicide rate with an effort to flood some of the city's most dangerous neighborhoods with officers working overtime.

After about seven weeks of sending at least a couple hundred extra officers out at night, there have been 23 homicides in the city. That's less than half the total from the same period a year ago.

Police Superintendent Garry McCarthy won't say the overtime work is the reason for the drop but says it's one of the department's top crime-fighting strategies

But the expense is enormous for the financially strapped city. The tactic could cost millions each month and eat up the department's entire overtime budget by fall.

McCarthy says paying overtime to officers on the force is cheaper than hiring new ones.