A balcony collapse on the NSW north coast has injured eight people attending a pre-wedding dinner.

The group were dining when the balcony on a second-storey building fell just after 8pm on Friday in Yamba, 60km northeast of Grafton, Chief Inspector Shari Allison told AAP.

The building has been evacuated and police were still investigating the scene on Saturday afternoon.

Eight people were treated at the scene, with four needing further treatment at hospital, police said in a statement.

A 60-year-old man was airlifted to Lismore Hospital in a stable condition while two women and another man were also transported to Grafton and Maclean hospitals respectively.
– AAP