Follow CBSMIAMI.COM: Facebook | Twitter

AVALON PARK (CBSMiami/AP)  – A construction crew using propane tools had been working in a central Florida Wal-Mart store where 13 employees were treated for carbon monoxide poisoning, authorities said Monday.

READ MORE: Mother's Day Flowers May Be Hard To Come By This Year Due To Global Pandemic

Fire rescue crews were called to the store after 3 AM Sunday when employees began complaining of headaches and dizziness. First responders detected very high levels of carbon monoxide and evacuated the Avalon Park store.

Orange County Fire Rescue spokeswoman Kathleen Kennedy told local media that levels of carbon monoxide reached 400 parts per million inside the store by 4 a.m. Sunday. Levels above 35 parts per million are considered excessive.

READ MORE: Peloton Recalling Nearly 125K Treadmills After Child’s Death, Several Injuries

Authorities say seven people were taken to the hospital as a precaution. Others were treated at the scene.

An investigation continued, but the store was cleared to reopen around 7:30 a.m. Sunday.

MORE NEWS: Endangered Venezuelan Orinoco River Crocs Hatch At Zoo Miami

(TM and © Copyright 2015 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2013 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)