Two people were transported to an area hospital following a carbon monoxide leak at Taco Bell, 200 Columbia Centre, in Columbia on Tuesday morning.

Columbia police, fire and EMS personnel responded about 10:30 a.m. The restaurant was evacuated as fire officials worked to rectify the situation.

Both patients are Taco Bell employees.

“They said they were dizzy and light-headed and feeling sick,” Columbia Assistant Fire Chief Jim Broshears said.

A high level of carbon monoxide was detected inside the restaurant, Broshears said. A low level of the colorless, odorless gas is typically 50 parts per million or less. Firefighters detected levels near 300 ppm inside the restaurant.

“That is very, very high,” Broshears said.

Broshears said the high readings were due to a malfunction of a motor in the restaurant’s ventilation system as well as a hornets nest found inside the vent pipes.

The restaurant was closed until maintenance could fix the problem, after which the fire department returned to check readings before reopening. Taco Bell was set to reopen about 5 p.m.

Broshears said Taco Bell did not have carbon monoxide detectors installed inside the restaurant.