MEXICO CITY — A helicopter crash killed Mexico’s second-most-powerful official and seven others on Friday, dealing yet another blow to the country’s battle against a drug-and-crime scourge and leaving a battered nation in shock.

The official, Francisco Blake Mora, 45, was the secretary of the interior and often the public face of the antidrug campaign. He was the second interior secretary to die in an air crash in three years.

There was no immediate word on the cause of the crash. President Felipe Calderón said it was probably an accident caused by bad weather, but his words did little to assuage the anxiety of a nation that has been pummeled by violence and pushed to trusting rumors by an opaque justice system that rarely provides evidence of innocence or guilt.

Stupefied and worried, many Mexicans could only imagine the worst. Offices came to a standstill as people tried to digest the news. Twitter and Facebook exploded with commentary, much of it presuming that some criminal group had brought the helicopter down.