The crash happened around 10:15 p.m. on Route 1 northbound, approximately one mile north of Smyrna.
Officials say four passenger vehicles and a van were slowed in northbound lanes in construction traffic when a large box truck failed to slow down and rear ended the vehicles.
The vehicles left the roadway with some of them overturning.
Police say a passenger in the first vehicle that was struck, identified as 7-year-old Bryan Kosc, was taken to Christiana Hospital where he was pronounced dead.
A 9-year-old from the same vehicle was flown to Alfred I. duPont Hospital for Children in serious condition.
Six other victims were taken to Christiana Hospital with non-life threatening injures.
The driver of the box truck, 28-year-old Bryan Hughes of Greenwood, was not injured.
Police are continuing to investigate this crash, but say alcohol does not appear to be a contributing factor. No charges have been filed.
The road was shut down for about four hours as crews cleared the crash.