An Oamaru baby was flown to Dunedin Hospital with serious injuries on Tuesday.

Police are trying to establish how an Oamaru baby suffered serious injuries on Tuesday afternoon.

The 14-month-old boy was flown from his home on the corner of Thames Highway and Foyle St to Dunedin Hospital in a critical condition on Tuesday night.

The property was understood to have been, intially cordoned off and a scene-investigation caravan had been seen outside.

A police spokesman said police were still trying to determine how the boy was injured, and a criminal investigation had not been launched.

A St John spokesman said St John was alerted to the incident at 4.13pm.

The boy was transported in a "very serious" condition to Oamaru Hospital before being airlifted to Dunedin Hospital, he said.