US cities see unexplained rise in violent crimes this year

Violent crimes ranging from homicides to rapes to robberies have been on the rise in many major U.S. cities so far this year.

But experts can't point to a single reason why and the jump isn't enough to suggest there's a trend.

Law enforcement officials are seeking a way to combat the problem.

Americans have grown accustomed to low crime rates since a peak in the 1990s. But law enforcement started seeing a spike last year that has continued unabated.

What's unusual is that it's not happening everywhere. While some cities like Chicago and Los Angeles are seeing homicides on the rise, others like Miami and Oakland are not.