V.G.
Flu? Stomach virus, or something they ate?
Little babies have stomachs that are a lot more sensitive than ours- I'd just make sure they drink a lot of fluids and keep an eye on them and the fever.
If the fever gets higher or your children get worse then I'd call the on-call nurse at the hospital to see if they need to go in.
As long as they're drinking water or pedialite they should be fine. :)