What does ‘shelter in place’ mean? What Americans in Mexico should know.

Americans in Mexico are being told to shelter in place following the death of cartel leader 'El Mencho.' Here's what the alert means.

Americans in parts of Mexico have been told to "shelter in place" until further notice by the U.S. State Department after the leader of the Jalisco New Generation Cartel was killed by the Mexican military on Feb. 22. The security order has meant that some Americans are stuck in the country while tensions wind down.

“Due to ongoing security operations and related road blockages and criminal activity, U.S. citizens in the named locations should shelter in place until further notice,” the agency said in its initial security alert.

In its latest update, the U.S. State Department has shrunk its number of locations under the shelter-in-place order, though some areas continue to see blockades and some flights continue to be disrupted. Here's what to know about the newest security alert for Mexico.

Americans have been told to shelter in place following Mexican drug lord Nemesio Rubén Oseguera Cervantes's death on Feb. 22. Known as "El Mencho," the cartel leader was killed in a military operation in Tapalpa, Jalisco on the morning of Feb. 22. Parts of Mexico have seen civil unrest in the wake of his death, including vehicles being torched and gunmen, believed to have supported Oseguera, blocking highways in a more than a dozen states.

The shelter-in-place alert was issued in response to the unrest and has continued into Feb. 23. According to the U.S. State Department, this means going inside a safe shelter, avoiding crowds, and being aware of your surroundings.