21.   Police suspect a gas leak caused the explosion.

22.   A gas leak caused a heavy explosion in the harbor district Sunday, destroying two houses and injuring ten people.

23.   A leak also caused a shutdown in the same reactor last October.

24.   A leak had caused their craft to decompress.

25.   A propane leak caused the explosion, Carlson said.

26.   Ammonia leaks can cause serious environmental risks.

27.   If the probe proves that a hydrogen peroxide leak did indeed cause the disaster, that could put some Russian navy commanders on the firing line.

28.   Investigators initially suspected that a gas leak had caused the blast.

29.   Officials suspect a gas leak caused the explosion, which destroyed dozens of apartments, ITAR-Tass said.

30.   One of those injured was a gas company worker, adding to police suspicions that a gas leak had caused the blast.