Armed offenders squad officers have cordoned off a house at Templeton, south of Christchurch.
Detective Senior Sergeant Neville Jenkins said police were called to an address on Trents Road, Templeton at about 6.30am.
Reports from witnesses were varied and the police were trying to establish exactly what occurred, he said.
Some witnesses had reported a firearms incident while others reported it was a motor vehicle crash.
The scene has been cordoned off and a scene examination is being carried out.
Police had deemed the property safe and were not aware of any injuries, but enquiries were underway, Mr Jenkins said.
Trents Road is expected to remain cordoned off for the next few hours.
A number of people who were in the area at the time are being interviewed.