Seven of the nine still hospitalized are in critical condition, said Trooper Gerald Bryant of the Texas Department of Public Safety.

"We may end up with even more fatalities before it's over with," Bryant said.

Investigators say that the right front tire of a Ford F-250 pickup truck packed with 23 people from Guatemala and Honduras came apart as the vehicle rounded a curve on U.S. Highway 59 near Goliad on Sunday night, pulling the vehicle to the right and causing the driver to slam into a tree.

It was the second multiple-fatality accident in the region in the past three months that involved smuggling people in overloaded vehicles.

In April, nine of 17 illegal immigrants in a packed minivan were killed when the vehicle rolled over while being pursued by U.S. Border Patrol agents near the border with Mexico in Palmview. The suspected driver, a 15-year-old boy, and six others, were charged in that crash.

Highway 59 is a well-traveled route for immigrant smugglers between the Mexico border and Houston. It was along that road, just northeast of the location of Sunday's accident, that a truck driver unhitched a milk trailer packed with dozens of undocumented immigrants in 2003. By the time officials opened the trailer, 19 people had died, and the picku p drive r was later sentenced to prison.

In Sunday's crash, it appears that the driver - who is among the dead - was smuggling illegal immigrants to Houston, where they hoped to find jobs, Bryant said.

The dead included 11 males and three females, Immigration and Customs Enforcement officials have said. Two children were among the dead.

Investigators have fingerprinted the crash victims and are working to identify them using photographs from people in Guatemala and Honduras who fear their relatives may be among the dead and injured. (Additional reporting by Jared Taylor in Edinburg, Texas; Editing by Corrie MacLaggan and David Brunnstrom)