Acting Essex County Prosecutor Robert Laurino says a December spike was largely due to three separate groups of young people who attacked drivers "for sport.''
Laurino says the groups have been significantly disrupted by recent arrests. On Monday, he announced the arrests of five juveniles and three adults on carjacking-related charges.
The arrests were made by a carjacking task force of federal and local law enforcement.
The prosecutor is seeking to charge all the juveniles as adults.