A Memphis police officer investigating a crash on Interstate 40 was hit and killed by a tractor-trailer. Memphis Police tweeted that 34-year-old Officer Darrell Adams was struck Saturday while investigating the two-car crash. He had worked for the department since April 2016. Memphis Police Chief Cerelyn Davis said the loss of a dedicated servant caused heartache. Police said the driver of the 18-wheeler was detained, but no charges have been filed. The Tennessee Highway Patrol was investigating.