Open Question: What do I write when asking if a position has been filled?

Last Monday I had a job interview for a bank teller position. The interviewer told me that by the end of the week they will call me to let me know if I qualify for a second interview or not. Now it's the beginning of the new week and I have heard nothing from the bank at all. I was advised to email the interviewer to see if the position has been filled, but I don't know how to properly phrase it without sounding desperate. How can I ask through an email if the position has been filled? AND, is it too soon to ask? Starting tomorrow (Tuesday) it will be about 7 business days since my interview.