All flights grounded until noon Wednesday

The first-ever grounding of all flights in the United States will remain in effect until at least noon EDT Wednesday due to security concerns following Tuesday's hijackings of airliners that were then crashed into buildings, the Federal Aviation Administration said.

The groundstop affects 36,000 to 40,000 flights that take off in the United States daily, as well as general aviation flights. Also, no flights will be allowed to come into the United States from other countries.