Armed police have descended on Johnsonville after a person was reportedly spotted with a firearm in the Wellington suburb.

A police spokesperson said some officers have been armed as a precaution.

A cordon was initially set up in the Broderick Road area but has since been stood down.

Enquiries are continuing but there is not believed to be any threat to the public.

Social media users have reported seeing several police cars racing to Johnsonville up the Ngauranga Gorge with lights flashing and sirens wailing.

Others have posted about seeing armed police outside Onslow College and Alex Moore park.

More to come.