Another dubious distinction it seems, the deadliest school disaster in the US. Not as many casualties as Texas City but perhaps a worse disaster in it's own way:
"The New London School explosion occurred on March 18, 1937, when a natural gas leak caused an explosion, destroying the London School of New London, Texas,[1] a community in Rusk County previously known as "London". The disaster killed more than 295 students and teachers, making it deadliest school disaster in American history. As of 2012, the event is the third deadliest disaster in the history of Texas, after the Galveston Hurricane of 1900, and the 1947 Texas City Disaster."
New London School explosion - Wikipedia, the free encyclopedia