Alton Middle School will be closed Tuesday due to a gas leak.
The leak was discovered late Monday morning. The school was closed and students sent home around 11:00 a.m.
Ameren crews thought they had contained the leak, but it's turning out to be a little tougher to repair than originally thought. So classes are cancelled while crews continue to work on it.
School officials say the closure is precautionary, since only a small amount of natural gas was detected inside the building.