The crash happened just before 2:15 p.m. on Monday in the Castle Hill section.
A 32-year-old man riding a motorized scooter westbound along the Cross Bronx Expressway near Ellis Avenue was struck by a Honda SUV also travelling westbound.
The driver of the scooter was taken to Jacobi Hospital in cardiac arrest. The victim later died.
The 22-year-old driver of the Honda was taken into police custody. Charges against the driver are pending.
The intersection where the accident happened was closed as police investigate.
This is breaking news. This story will be updated as more information becomes available.
----------
* More Bronx news
* Send us a news tip
* Download the abc7NY app for breaking news alerts
* Follow us on YouTube