Eight migrants trying to enter the U.S. along the southern border were found dead in the Rio Grande, according to Customs and Border Protection (CBP), which discovered the bodies on Thursday when responding to an illegal crossing attempt by several dozen migrants near Eagle Pass, Texas.

Border Patrol agents apprehended 53 migrants during the incident, officials said, including 37 individuals who were rescued from the river, which divides the U.S. and Mexico. Mexican officials took custody of an additional 39 migrants on the other side of the Rio Grande, CBP said Friday. 

U.S. border officials recovered six of the deceased bodies, while their Mexican government counterparts discovered two bodies, according to a statement released by CBP. Richard Pauza, an agency spokesperson, said the bodies were discovered inside the river. 

“Border Patrol agents are coordinating with the Eagle Pass Fire Department and Maverick County Sheriff’s Office as the search continues for other possible victims,” Pauza added.

Unlawful crossings along the U.S.-Mexico border can sometimes be deadly. CBP has tracked deaths of migrants in the Rio Grande, remote areas of the borderlands and canals. Last week, Mexican officials reported the drowning of a 5-year-old Guatemalan girl who was trying to cross the Rio Grande with her mother.

Even when migrants successfully enter the U.S., the migration journey can still be fatal, as illustrated by the deaths of 53 migrants in an abandoned tractor-trailer in Texas earlier this summer, the deadliest suspected human smuggling case in U.S. history.

The International Organization for Migration, a United Nations affiliated group, reported 728 deaths of migrants along the U.S.-Mexico border in 2021, a record that officials said is likely an undercount due to data collection limits.

Like many other parts of the U.S.-Mexico border, the Del Rio, Texas, sector where the latest suspected drownings occurred has seen an unprecedented increase in migrant arrests over the past year. Border Patrol agents in Del Rio recorded 376,000 migrant apprehensions in the first 10 months of fiscal year 2022, a 45% jump from 2021, CBP data show.

U.S. immigration agents along the Mexican border have reported more than 1.8 million apprehensions in fiscal year 2022, a new record high that will likely surpass 2 million when fiscal year 2023 starts in October, according to the CBP figures.