Popocatépetl volcano prompts evacuation warning in Mexico.

Millions of people in Mexico have been warned to prepare for a possible evacuation as the Popocatépetl volcano, the country's most dangerous active volcano, has been spewing ash into several nearby towns since last week. The National Civil Protection Coordination (CNPC) increased its volcanic threat level to "yellow phase 3," calling on some 3 million people who live in towns and villages adjacent to the volcano to stay alert and prepare for a possible evacuation. The volcano's activity has delayed flights in Mexico City and led authorities to close schools in dozens of municipalities.