"No one seems to know what happened," he said.
"About 100 people, including surf lifesavers, coastguard, police, St John and members of the public, have been looking for her.
"There's only about half an hour or an hour of daylight left so the search will probably have to stop soon."
He understood the girl's parents had alerted emergency services after about 20 minutes of her not returning home.
It was a beautiful day and several people had been at the beach, he said.
Police said earlier the national dive squad was on standby and the search would continue until dark.
Eastland Port and the Gisborne District Council began a safety review of Butlers Wall after a 19-year-old hit his head on a rock during a wall jump and suffered a serious spinal injury.
Port general manager Andrew Gaddum said new signage would be put up to deter people jumping off the wall.