Vehicle thefts are on the rise again in North Carolina after a decade-long decline.

The State Bureau of Investigation says 15,007 vehicles were stolen in North Carolina in 2016. That was nearly 4,000 more stolen vehicles than the year before, but a steep decline from the nearly 30,000 stolen vehicles reported in 2006.

Authorities aren’t sure what caused the increase, but say new technology that allows thieves to intercept a key fob signal and replicate it so the car can be stolen could be a factor.

Steven Watkins of the Division of Motor Vehicles told The News & Observer of Raleigh that car thefts could be cut in half if people didn’t do careless things like leave vehicles unlocked or running when they go inside stores or in the mornings.