2005 Kia Sorento gas backing up

I am out of town and my wife called me and said the engine light went on in her Kia. She stopped to get gas before she went home as she was on empty. She told me that as she initially was putting the gas in it started to flow backwards and back out. She then stopped because she was not sure what was going on. Only about 1/4 of a tank was filled. Any idea on what needs to be fixed. Thankyou!