It happened around 1:45 a.m. on the eastbound 10 Freeway at Pepper Avenue.
The car hit a tractor-trailer in the construction zone while going about 70 mph and then rolled over.
Some of the passengers were ejected from the vehicle.
All six people inside the car -- ranging in age from 15 to 20 -- were transported to the hospital.
Some were taken to Loma Linda University Medical Center, and others were at Arrowhead Hospital.
A 17-year-old who was sitting in the back seat on the passenger's side was in critical condition with a broken neck.
Four others had injuries ranging from a lacerated liver to head wounds.
Nobody was wearing a seat belt, according to the CHP.
The driver of the car, who is 18, was given a field sobriety test at the scene and then arrested.
He was being cleared at the hospital before being booked at the West Valley Detention Center on suspicion of DUI.
The CHP says other charges are pending, because it appears all the occupants of the vehicle were drinking, and they are all minors.
Fortunately, no Caltrans workers were hurt.
"The message that we send out to all drivers driving on the freeway is to be careful, watch their speeds and be courteous," one CHP officer told KTLA. "Just pay attention to the roadway."
Last Thursday, 21-year-old Connor Penhall was struck and killed while doing construction work on a closed section of the 10 Freeway in Baldwin Park.
The driver, 37-year-old Tatsuhiko Sakamoto, of Arcadia, has been charged with vehicular manslaughter while intoxicated.
Penhall was the son of motorcycle speedway racing legend and actor Bruce Penhall.