The armed offenders squad has been called to an address in St Heliers after reports of a person seen with a firearm.
Police were called to an address on St Johns Rd at 6.30pm.
A police spokeswoman said there was no indication that shots had been fired and the situation appeared to have been contained to one address.
However, the situation was ongoing, she said.
Police have cordoned off the driveway of a group of three units at top of the road near the St Heliers Bay Rd intersection.
Two officers, one in a white decontamination suit and another in uniform, are talking to somebody one the steps of the middle house.
A neighbour said helicopters had been circling for about 15 minutes.
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