Everyone knows cell phones in cars can be deadly. And now, a new study suggests that mobile devices are killing more pedestrians, too.

A 10-percent spike in pedestrian fatalities in the first six months of last year – the largest year-to-year increase in such deaths in four decades – may well be fueled by America’s increasing distraction with mobile devices.

Lower gas prices and more road trips last year are other possible culprits, according to the Governors Highway Safety Association report. But the cell phone’s iconic hold on attention could be having deadly consequences.

“There’s never been a 10% increase in just one year,” said Richard Retting, co-author of the report. “Looking at cell phone data and how much is used — it’s explosive; it’s beyond an incremental increase and those could be factors that come into play.”