The doors are back open at a Christchurch social development branch -- after a short lockdown this morning

MSD says the Linwood service centre, along Aldwins Rd, was closed following a threat this morning around 8.50am.

Police are speaking with one person -- after a man was taken into custody.

Reporter Tim Cronshaw, who is at the site, says awaiting customers queued outside the building as the drama unfolded.

He says around 10 people queued were standing in line outside the site -- and a few were very unhappy to be kept waiting.