By Corrie MacLaggan
AUSTIN, Texas (Reuters) - U.S., Texas and Mexico officials are investigating whether any suspected drug runners may have been killed in a Thursday morning border shootout with U.S. law enforcement, Texas Department of Public Safety officials said on Friday.
The incident began when U.S. Border Patrol officials in South Texas' Hidalgo County pursued a Dodge Durango -- which they suspected was carrying drugs -- as it made its way toward the Rio Grande on the Mexican border, said Department of Public Safety spokeswoman Lisa Block.
The suspected smugglers transferred their cargo onto rafts, crossed to the Mexican side, and were unloading drugs from the raft when they were approached by several U.S. law enforcement boats carrying officials from the Texas Parks and Wildlife Department, the Border Patrol and the Texas Rangers, she said.
As the boats approached, the suspects "started throwing rocks and then opened fire onto the officers and the officers returned fire," Block said.
She said preliminary information indicates the suspects discharged at least six gunshots, though that is still under investigation. American officials appear to have shot some 300 rounds, she said.
"If someone is pointing a rifle at an officer, that officer has the right to protect themselves," Block told Reuters on Friday. "We want them to go home safe to their families."
Mexican officials recovered 400 pounds of marijuana from the scene but were "unable to arrest anyone," she said.
When drug smugglers can't get a load into Texas, "they want to take it back to Mexico so they can try again," Block said.
The Department of Public Safety reported on Thursday that at least three suspected drug runners were wounded. Officials are investigating whether any may have died, Block said.
Two game wardens with the Texas Parks and Wildlife Department were injured when they were hit by large, jagged chunks of concrete the suspects threw at them, department spokesman Mike Cox said.
One was hit in the elbow and the other had cuts on his arm and abrasions to his face, Cox told Reuters on Friday.
Texas officials, along with the Federal Bureau of Investigation and U.S. Customs and Border Protection, are working with Mexican officials to investigate the incident, Block said.
"It's very unusual because the (Department of Public Safety) and the Texas Rangers have not been fired on in years down on the river," she said.
U.S. Sen. John Cornyn, a Texas Republican and a member of the Senate Judiciary Committee, seized upon the incident that he called a "brazen attack" to criticize President Barack Obama's administration.
"Cartel-related violence along our border is real and escalating, and the Administration cannot continue to deny it when American lives -- particularly those of our law enforcement -- are directly in harm's way," Cornyn said in a statement.
(Additional reporting by Karen Brooks; Editing by Jerry Norton)