Two police officers have been shot – one reportedly killed – and a gunman is still active in south-west Pennsylvania, according to local media report.

Police told residents to stay inside their houses on Thursday as they searched for the gunman in the town of Canonsburg about 40 kilometres south-west of Pittsburgh.

There were no immediate details on the condition of the second officer or what led up to the attack at about 4am local time.

One of the officers was flown to a hospital in Pittsburgh and the other was taken by ambulance to a hospital in Canonsburg, WPXI.com reported.

Authorities said schools would open two hours later than usual as the investigation continued.

More to come.

Reuters