1.   In the Challenger disaster, hot gases leaked through the rocket joint, igniting the hydrogen fuel tank.

2.   Inspect the fireplace periodically for cracks in the flue or chimney that could allow combustion gases to leak back into the house.

3.   When gas leaks into the soil, MTBE contaminates water supplies.

4.   A warning was issued to nearby residents because noxious chemical gas still was leaking several hours after the explosion, said a spokesman at Aizu-Wakamatsu Police Station.

5.   But once the gas leaked, it removed all the oxygen in the room.

6.   Chlorine gas leaked from a storage container and filled a gorilla habitat at a zoo Sunday, killing three animals.

7.   Gas officials were investigating what caused the gas to leak.

8.   Gas leaked through badly welded seams in the pipe, accumulated in the cafeteria basement and eventually exploded, Ambarian said.

9.   In that accident, gas leaked while workers were installing a new gas system, mixed with air and ignited.

10.   Preliminary investigation shows a gas leak caused the explosion Tuesday that ripped through the nine-story building, destroying the top five floors.