Mexican volcano spewing ash and rock, affecting air travel

A volcano in Mexico has forced several U.S. airlines to cancel dozens of flights, including out of Phoenix . Earlier this week, authorities recorded several tremors at the 18,000 foot Popocatepetl volcano. It has been spewing a fountain of ash, steam and glowing rocks since Wednesday.

Airport officials say six U.S. airlines, including US Airways, Delta and United have cancelled flights to the Mexico City and Toluca airports as a precaution. That has affected travelers in cities including Phoenix , Denver and Houston .

The volcano sits about halfway between Mexico City and Puebla . Airport spokesmen said despite the volcanic activity, things are running normally. The Mexico City airport said the ash has not yet reached them.