A sport utility vehicle packed with illegal immigrants rolled over Thursday on a rural highway southeast of Phoenix, killing nine people and injuring the other 10 on board, authorities said.

The passengers were crammed into a Chevrolet Suburban with two bucket seats in front and three seats in the back, said Lt. Mike Corbin of the state Department of Public Safety. All the dead and injured were trapped inside the crumpled vehicle and had to be extricated, officials said.

"We have cause to believe that this was a human smuggling operation, and so the people involved were illegally in the United States," said Vinnie Picard, a spokesman for U.S. Immigration and Customs Enforcement.

The SUV crashed on a state route about 80 miles from Phoenix, Public Safety spokesman Bart Graves said.

Authorities say immigrant smugglers are increasingly staying off interstate highways, even though the bumpy, narrow roads they use as alternatives are tougher to negotiate at high speeds.

Lt. Mike Corbin of the Public Safety Department said the Suburban was heading north just before 8 a.m. Thursday when it ran off the road, crossed a dry wash, slammed into a concrete abutment on the other side and flipped over. The roof caved in when the SUV rolled.

A witness who was driving in front of the crashed SUV reported that it was approaching him fast when it veered off the road, Corbin said. The Border Patrol and other agencies said they had no knowledge of the SUV until after the crash.

All the victims were adults, and all but two were men. The women both died at the scene, Corbin said.

The conditions of all 10 injured were not immediately available, but two of them were critical at a Tucson hospital. Continued...