Mexican authorities say a pre-dawn shootout near the U.S. border has left three suspected drug traffickers dead and six other people wounded.

Officials say the gun battle happened Friday in Nuevo Laredo when local police tried to stop a convoy of armed men who began shooting at them.

Officials also say federal police and army troops were called in to provide backup and that the soldiers fired on the suspects' cars with rocket-propelled grenades.

Authorities say the convoy appeared linked to an attempt by traffickers from other areas to move into territory controlled by the Gulf Cartel. The group operates in northeastern Mexico.

The shootout occurred less than one day after U.S. and Mexican officials announced the arrests of more than 240 people in a 19-month operation targeting Mexico's Zambada-Garcia drug cartel.

The cartel leader, Ismael Zambada-Garcia, and two deputies, have also been indicted as part of the investigation known as "Operation Trifecta." They are charged with trafficking in cocaine, marijuana and methamphetamine.