Connie was speaking after the issue came to light earlier on Friday.
She added: “Serious questions need asked to the education authority around incidents like this, which isn't the first of its kind. My thoughts are with the child involved, who has been through a terrifying experience.
“The child was not escorted off the bus at their school, the driver then went to Lidl to go shopping and the child was left alone on the bus. The child with Down's syndrome then got off the bus alone with teachers and parents unaware of his whereabouts.
It's hard to comprehend how this could have happened, and the potential dangers the child was exposed to. Parents need to have full confidence in EA services and their children's safety. There must be serious efforts made to ensure this doesn't happen again.
“I will raise with the Education Minister and EA Chief Executive. Alliance representatives on the EA board will also be addressing this.”