SAN DIEGO (NEWS 8) — A shark sighting over the weekend in Carlsbad is causing concern.

Surfers and swimmers were warned not to wade into the water after a 10-foot shark was spotted just off shore.

That sighting happened Saturday morning at South Ponto Beach near Tower 20.

A surfer told lifeguards it was about 20 feet away from where he was in the water.

"There was no aggressive activity that was displayed by the shark or reported," said lifeguard Sgt. Jake Pflepsen.

Because of that "non-aggressive" behavior, a 24-hour advisory was put out and signs were posted within a mile radius of the area.

The surfer told officials he first saw the fin, and that it looked as though the shark was 10 feet long.

Beyond that, it's unclear what species it was.

The last sighting in the area was a year ago.

Lifeguards want to assure people despite the sighting - it is now safe to go in the water.

But they say, if you do see something it's always a good idea to report it to lifeguards.