Brownsville, TX (KRGV) — Mexican authorities are investigating whether gunfire from a Tamaulipas State Guard helicopter killed a 7-year-old girl during Friday's move to capture an accused cartel boss in Matamoros, according to a statement from the governor of Tamaulipas.

The shootout led to a temporary shutdown of the international bridges in Brownsville.

Tamaulipas Gov. Americo Villarreal Anaya also confirmed six people died during the capture of Axel Cardenas Rodriguez. Mexican authorities say he was second in command of the Los Ciclones faction of the Gulf Cartel.

President Donald Trump designated the Gulf cartel as a foreign terrorist organization.

"U.S. authorities have open investigations against the leaders of these criminal organizations. It's hard for me to tell you the exact reason why there was this detention. Authorities have been behind him for quite some time," Mexico security expert David Saucedo said.

Mexico's federal government sent 450 military personnel to Matamoros over the weekend to reinforce security. The father of Axel Cardenas Rodriguez, José Cárdenas Martínez, is currently facing U.S. drug trafficking charges.