Mexico's top security official says that "security is deficient in almost the whole country," after a large group of migrants went missing in northern Mexico.

Public Safety Secretary Alfonso Durazo says the number of men pulled off a bus last week in the border state of Tamaulipas has been reported as anywhere between 19 and 25.

Durazo said Tuesday the conflicting reports came from investigators and the bus driver.

The driver said hooded men pointed guns at the bus and later climbed aboard with a list of names of those they abducted. All were apparently migrants and may have contracted human traffickers to be smuggled into the United States, but they weren't part of a caravan.

Durazo said Mexico simply doesn't have enough police to cover the whole country.