Police have spent the night examining the scene of a dramatic operation which took place in Christchurch's Richmond yesterday

Around 5pm yesterday - witnesses described seeing a dozen police cars lining North Avon, McLeod, and Avalon Street.

Newstalk ZB reporters saw armed offenders squad officers trying to force their way into a property.

At the time about 100 locals gathered to watch the operation from outside the police cordon.

A police sergeant says it was an isolated incident - with officers hoping to be off the scene this morning.