Melissa Jimenez thought the worst when her son wasn't at Kool Kids Day Care on Monday.

"I was just in panic mode," said Jimenez. "I had my co-worker drive me because I was just an emotional wreck."

While on the phone with police, she rushed home. When she got there she found her 7-year-old son outside, alone, in the scorching sun.

"He was outside in the heat with no water, no food, nothing to drink. My house is locked. Because he's only seven years old, he doesn't have the key to the house," said Jimenez.

A Pasadena Independent School District spokesperson said they're to blame.

The child goes to Genoa Elementary School and on Monday he had a substitute teacher. Jimenez's son got in the school bus line, but he was supposed be in the day care bus line.

That substitute teacher violated school policy by not checking to make sure the child was in the correct line.

In a statement, a district spokesperson says, "The district failed to follow the proper procedure on Monday to assure this child got home safely. Thankfully, the child was unharmed. The campus principal has used this opportunity to review with the staff the correct procedure for dismissing students."

The substitute teacher, the principal, and the superintendent have all apologized to Jimenez. But she says it's not enough and it's time for a policy change.

"There should be some type of check-off list like, hey these kids are bus riders, these kids are car riders, these are day care people," said Jimenez.

Pasadena ISD's spokesperson says this is the first time something like this has happened at Genoa Elementary.

She says at the beginning of the school year, the district may have a mix-up but it's rare and she doesn't have any numbers on incidents.

Click here to read the full statement from Pasadena ISD.