A Mexican national pleaded guilty to four offenses related to a human smuggling event near the Rio Grande, according to a news release from the office of U.S. Attorney Nicholas J. Ganjei.

The news release said 39-year-old Alejandro Ramirez-Carranza, from Matamoros, Tamaulipas, admitted to transporting undocumented migrants in to the United States as well as entering the country illegally while in possession of a firearm.

According to the news release, Mexican citizen Isaac Azuara-Vasquez, 39, pleaded guilty on April 10 to the same smuggling-related charges as well as selling a firearm to Ramirez-Carranza.

Authorities were conducting surveillance on February 12 in an area "notorious" for human, drug and weapon smuggling when they heard a boat in the Rio Grande, according to the news release.

After hearing someone tell people to run in Spanish, law enforcement saw a truck driving toward the river, according to the news release. The vehicle stopped by the river's edge, and several individuals ran out of the brush and climbed into the truck bed.

The news release said Azuara-Vasquez was driving the truck and had brought an AR-15 weapon. Ramirez-Carranza was standing nearby and retrieved the firearm before running toward the back of the truck. He ignored multiple commands from law enforcement to stop and drop the weapon.

The investigation revealed Ramirez-Carranza was the river guide and had conspired with Azuara-Vasquez to transport and smuggle the individuals found in the truck. One of the individuals indicated Ramirez-Carranza brought him across the Rio Grande by boat and that his family paid him to be smuggled into the country, according to the news release.

The news release said Ramirez-Carranza has felony convictions for unauthorized use of a motor vehicle and entering the country illegal after deportation. He was last removed from the U.S. in September 2009.

Azuara-Vasquez and Ramirez-Carranza are scheduled for sentencing on July 2 and July 30, according to the news release. They face up to 10 years in prison for human smuggling and a maximum of 15 years for their firearm offenses, according to the news release. Ramirez-Carranza faces another 10 years for entering the country illegally. All convictions also carry potential fines of up to $250,000.

Both have been and will remain in custody pending sentencing.