It hasn't been a great morning for Wellington train commuters with a string of incidents, including a fire evacuation at Wellington station, causing multiple disruptions to services.

All rail services were suspended out of the capital's main station at 7.30am on Wednesday after it was evacuated for 20 minutes, according to Metlink.

That caused the cancellation of the 7.25am Upper Hutt service but all other services were only expected to have minor delays.

Meanwhile, those travelling on the Wairarapa line are facing a slow commute with both the 6.20am and 6.47am trains from Masterton delayed.

The earlier service was delayed at Waterloo Station for 23 minutes following a medical emergency.

The later service is being held outside Maymorn Station after a truck hit a bridge.