UPDATED 8.24PM: A rogue baggage trolley set off sprinklers and triggered fire alarms at Wellington Airport, causing the airport to be evacuated, an unnamed airport staff member has confirmed.

The terminals have now reopened and flights are boarding again.

Earlier, a witness said there was "chaos at the check-in counters" as flights were delayed.

The airport was evacuated after fire alarms went off at 6.20pm. 

At least one fire crew arrived at the airport and people were told to head outside.

Airport spokesman Greg Thomas said there was no fire, but a sprinkler had been knocked - triggering a full fire alarm.

Fire alarm and everyone evacuated at Wellington airport right now pic.twitter.com/chp9aQxh6u

— Laura Tupou (@LauraTupou) July 10, 2016