This is the first official NASA statement of any note on the loss of the Shuttle Columbia...

NASA STATEMENT ON LOSS OF COMMUNICATIONS WITH COLUMBIA

A Space Shuttle contingency has been declared in Mission Control, Houston, as a result of the loss of communication with the Space Shuttle Columbia at approximately 9 a.m. EST Saturday as it descended toward a landing at the Kennedy Space Center, Fla. It was scheduled to touchdown at 9:16 a.m. EST.

Communication and tracking of the shuttle was lost at 9 a.m. EST at an altitude of about 203,000 feet in the area above north central Texas. At the time communications were lost. The shuttle was traveling approximately 12,500 miles per hour (Mach 18). No communication and tracking information were received in Mission Control after that time.

Search and rescue teams in the Dallas-Fort Worth and in portions of East Texas have been alerted. Any debris that is located in the area that may be related to the Space Shuttle contingency should be avoided and may be hazardous as a result of toxic propellants used aboard the shuttle. The location of any possible debris should immediately be reported to local authorities.

Flight controllers in Mission Control have secured all information, notes and data pertinent to today's entry and landing by Space Shuttle Columbia and continue to methodically proceed through contingency plans.

FMI: www.nasa.gov