Four men were found dead at the scene. Four more male passengers were taken by air and ground ambulances to St. Mary's Hospital in nearby Grand Junction, Colo., in conditions ranging from critical to serious.
Royce did not immediately know the victims' ages or names.
A ninth van occupant, a female, walked away from the scene and had not been located as of about 2:45 p.m. Friday.
Witnesses not involved in the crash had seen her, said Trooper Jalaine Hawkes. It was not immediately clear whether she is an adult or a juvenile and which direction she was going.
The Department of Homeland Security is trying to confirm the identities of everyone involved and is looking into the incident as possibly involving human smuggling, Hawkes said.
All lanes of I-70 were closed for a time, but were reopened by about 1 p.m.
On Oct. 11, 2005, a van carrying 15 people including 14 who allegedly had entered the country illegally rolled near Moab. Two passengers, Guatemalans Juana Ixcuna-Chich and Amalia Perez-Lucas, were killed.
Three years later, Raul Ramirez-Becerra, then 27, pleaded guilty to a charge of transporting undocumented immigrants resulting in death and was sentenced to 30 months in federal prison.
Ramirez-Becerra, who was also a passenger in the van, walked away from a Moab-area hospital and was a fugitive until his arrest in Phoenix in 2007.
His co-defendant, Noe Luna-Escalona, was driving the van when he fell asleep and drifted off U.S. Highway 191. He overcorrected and rolled the 2000 Dodge Caravan.
Luna-Escalona, 18 at the time, had agreed to a request by Ramirez-Becerra to drive. He was sentenced in 2006 to 24 months in prison.