"The accident happened because [the driver] lost control, and once she lost control, speed played a factor as to why she couldn't regain it," a law enforcement source told the New York Post.
The driver, Maria "Fina" Gonzalez, 45, was killed in the Bronx River Parkway accident Sunday, along with her 10-year-old daughter, her 3- and 7-year-old nieces, her sister and her parents, the Post said.
The SUV landed in a wooded area of the Bronx Zoo.
The Post reported Wednesday the New York Department of Transportation would install concrete barriers along the outside lanes and reduce the speed limit along the elevated portion of the Bronx River Parkway where the accident occurred.
A family attorney has set up a fund to help cover burial costs.
Checks can be made out to "Juan Gonzalez as Trustee" and sent to attorney Jose Antonio Rodriguez, 644 Soundview Ave., Bronx, N.Y., 10473.