Firefighters evacuated workers from the Masterton Railway Station building yesterday morning after reports of gas fumes at the site.
Masterton fire station officer Doug Flowerday said firefighters were at the premises for about 30 minutes, from about 10.30am yesterday.
The firefighters cordoned off the entrances to the station and evacuated rail staff and Rideshop workers from the station building.
Firefighters used breathing apparatus and a gas detector to monitor the building for leaks, shut down the gas supply and ventilated the premises.
"We think it was probably a faulty heater unit that caused a small gas leak inside the building," Mr Flowerday said.