Amazon packages move along a conveyor. Credit: Ross D. Franklin | AP

NASHUA, New Hampshire — Three employees were sickened by a cleaning chemical at an Amazon warehouse in New Hampshire, fire officials said Thursday.

Firefighters in Nashua responded at about 4 a.m. for a report of a chemical reaction that happened while a crew was mixing chemicals, Deputy Fire Chief Karl Gerhard told WMUR-TV.

“The major symptoms we saw were respiratory-related, scratchiness, coughing-related issues,” Gerhard said.

Gerhard said, “there was possibly an unknown chemical in the bucket already that they were putting the chemicals in, and that caused the reaction.”

The building was evacuated and the employees were taken to a hospital. Two were treated and released.

A fire department report said after the building had been ventilated, crews monitored the building using air and chemical metering devices and found no abnormal readings.

OSHA and the state fire marshal’s office were notified.