There is a heavy police presence in the Christchurch suburb of Burnside as police investigate the deaths of an elderly man and woman.

Officers were called to the home on Wairakei Road in Burnside just after 4am.

A worker at the Z Burnside petrol station says she saw police officers putting down cones in front of Grahams Road early this morning.

A neighbouring resident says he heard two sounds ring out which may have been gunshots or tear gas.

Canterbury District Commander Superintendent John Price says a scene examination is underway and a post mortem will be carried out in the coming days.

He says they're not seeking anyone in relation to the incident - and residents are safe.