Mexican security forces in the city of Tijuana, on the border with the US, have seized 105 tons of marijuana - the largest such drug haul for many years.
Eleven people were arrested during the operation, during which one police officer and one suspect were injured in exchanges of gunfire.
The drugs were found wrapped in 10,000 packages, in houses and vehicles.
They have a US street value of more than $340m, the Mexican military said.
"The seizure of these drugs is without precedent in the country," General Alfonso Duarte told reporters.
Soldiers and police found the drugs in pre-dawn raids in three neighbourhoods in Tijuana, a city across the border from San Diego, California.
Gen Duarte said the packages were still being counted and weighed and the amount could increase. The marijuana would be incinerated once all packages had been registered, he added.
The general said local gangs had been preparing to smuggle the drugs into the US, but he did not identify the gangs or say where the marijuana originated.
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