Fort Worth, TX – The Fort Worth Fire Department has cleared Diamond Hill Elementary School for occupation after several adults were taken to the hospital complaining of nausea. One doctor suspected possible carbon-monoxide (CO) poisoning was the cause which prompted an evacuation at the school.

At one point Medstar said at least fourteen people were being treated for possible carbon-monoxide (CO) poisoning. They said thirteen people had minor complaints and one had “serious but non life threatening” complaints.

An official with the Fort Worth ISD tells CBS DFW that a teacher left campus feeling ill and went to her doctor who told her she had symptoms of CO poisoning. “We evacuated building in an abundance of caution and asked [the fire department] to check,” said Clint Bond, the Director of External & Emergency Communications for the Fort Worth Independent School District.

Bond said the Fort Worth Fire Department found no evidence of any gas within the building but that some construction nearby may have been an issue. “There was construction activity on campus but outside the school building. Workers were using a gasoline powered cutting tool,” said Bond. “There has been no determination if fumes from that tool caused anyone to feel nauseous. As a matter of caution the use of that tool has been curtailed for the remainder of the day,” he continued.