The crash occurred in Fairfield County on the southbound side in Stamford around 7:30 p.m., Saturday, July 1.
According to Connecticut State Police, an 18-year-old Stamford man was driving a 2013 BMW X3 at a high rate of speed when he attempted to change lanes and struck two cars.
The BMW then rolled over, police said.
Shortly after, a fourth vehicle ran into one of the cars involved in the initial crash, lost control, and flipped over.
The girl, a resident of Stamford, suffered serious injuries and was transported to Stamford Hospital, she was later transferred to Yale-New Haven Hospital. Five others were taken to Stamford Hospital with suspected minor injuries, police said.
State police did not say if the BMW driver was charged.
The crash remains under investigation.
Anyone with information is asked to contact Trooper Carmen Quispialaya via email at Carmen.Quispialaya@ct.gov.
Check back to Daily Voice for updates.
Click here to follow Daily Voice Danbury and receive free news updates.