Story highlights The crash occurred in southwestern Mexico

One survivor is in intensive care

(CNN) Authorities are investigating if criminals were involved in a police helicopter crash that killed four people in southwestern Mexico, a local governor said.

Three police officers and a pilot died Tuesday when the aircraft went down in Michoacan state, Gov. Silvano Aureoles tweeted.

At the time, Aureoles tweeted that criminals downed the aircraft. But in a later interview with CNN affiliate Televisa, he said he "cannot confirm that it was taken down, or shot down."

An investigation is underway to determine the cause of the crash.

A survivor of the crash is in intensive care, and will be instrumental in helping determine what happened, the governor said.