Dunedin's Mayor is urging caution after a spate of violent incidents in the city.

Over the last week a woman has been attacked while out running, another while on her bike, and a third was killed late at night.

Police have been searching the home of a woman - she and the dead woman are both associated with the same company.

Mayor Dave Cull believes the clumping of attacks is a coincidence.

"It doesn't mean people shouldn't be concerned, and certainly until the offenders are brought to book, I think people - particularly women - should be careful in certain areas of the city."

Cull said there was a great deal of planning involved in the sexual assault, but the others came out of the blue.

"In a sense there's nothing that the community can do to prepare or prevent in some circumstances that sort of thing, you just have to deal with it."

"But Dunedin is probably one of the safest communities in New Zealand" added Mayor Cull.