Correction: An earlier version of this story should have said two people were detained in connection with the fire; they were not taken into custody.
UPDATE 5:04 p.m.: The forward spread of the Oceano Dunes fire has been stopped at around 4 to 5 acres, and no structures are threatened. However, a ground crew remains on the scene, and a helicopter is circling the area to "keep an eye on it," Cal Fire information officer Tina Rose said.
Two people were detained on suspicion of starting the fire, but it has not been determined if it was set accidentally or intentionally, Rose said.
Original story: Cal Fire is responding to a fire on California State Parks land at the Oceano Dunes.
The fire, which has burned 4 acres, reportedly started just before 4 p.m. north of Pier Avenue. Cal Fire information officer Tina Rose said that initial dispatches indicate that structures are threatened.