Apex, N.C. — Salem Elementary School in Apex dismissed students at 12:45 p.m. Wednesday after the school's air conditioning malfunctioned.

The school said it notified parents, but some say they never got the word. That meant some children got off buses while their parents were at work.

Tia Williams and her husband had just sat down for lunch when an unexpected visitor showed up at their door.

“She came up and rang the doorbell and I went and opened the door, and I was kind of surprised to see her,” Williams said.

The person at the door was her 10-year-old daughter, who was supposed to be in school.

“She said, 'Hey, I got out of school early today. The air conditioner is broken and it got too hot in school, so they sent us all home,'”  Williams said.

When three large fan motors went out on the school's air-conditioning unit, administrators called in the buses early and sent phone messages to parents.

The problem: many parents never got word until the children got off the bus.

“It is frightening,” Williams said.

WRAL talked with several other families in Williams' neighborhood. Most said they got a message at home, but not at work or on their cell phones.

“As far as we know, the system worked as it is supposed to,” Wake Schools spokesman Greg Thomas said.

Thomas said Salem Elementary and the Wake County school system sent calls to every contact phone number listed for each child before the early release.

“It will call all of them. And that's why it's really important for parents to make sure that they get updated contact information back to the school,” Thomas said.

The school system also posted a notice on its Web site and notified news media to help spread the word.

Thomas said the school’s principal on Thursday looked into the process of gathering data for the emergency call system. The school wants to make sure they have all contact numbers and the correct numbers.

Williams said she recently updated new contact phone numbers, and others have been the same for years.

“I did check my voice mail. I checked my cell phone voice mail. I didn't hear anything from the school,” she added.

Parents like Williams hope the school will review the phone system before calling it an early day again. School administrators said they will double-check the system for any possible problems.

The air conditioner was repaired while the children were at home, and Salem Elementary is scheduled to reopen Thursday morning.

The county school system is looking into the technology-aspect of the call system. The department found some flaws with how the data is transferred to the vendor, Thomas said. Most of those flaws were corrected Thursday. The remaining flaws will be corrected as soon as possible, he said.