An armed attack on a Mexican military convoy which left five soldiers dead and ten wounded was most likely orchestrated by sons of jailed drug kingpin Joaquin "El Chapo", a senior security official said.
The ambush took place in the early Friday morning hours near the city of Culiacan in northern Sinaloa state, along Mexico's Pacific coast.
General Alfonso Duarte, the regional defence ministry commander in charge of Sinaloa said the convoy was transporting a detainee, Julio Ortiz when armed men hurling grenades ambushed it causing two vehicles in the convoy to burst into flames.
Allegedly Ortiz was involved in a dispute over control of drug crops between Aureliano Guzman, a brother of "El Chapo", and Alfredo Beltran, a leader of the rival Beltran Leyva cartel.
It is unclear whether Ortiz, who was taken alive by the attackers, is an ally or an enemy of the armed men.
"We aren't sure (about the identity of the attackers), but it's very probable that they work for the sons of El Chapo," Duarte told reporters at a joint news conference with Sinaloa Governor Mario Lopez.
"It was a cowardly attack since the soldiers, unfortunately, didn't have a chance to defend themselves," said Lopez.
Mexican President Enrique Pena Nieto promised to bring those responsible to justice in a post on his Twitter page.
"El Chapo" Guzman was re-captured earlier this year following his brazen escape from a maximum security prison in July of last year.
He is currently imprisoned in Ciudad Juarez, a northern Mexican city on the US border, awaiting extradition to the United States.