The fire was burning as of shortly before 1 p.m. in the area of Wood and 26th streets, Oakland Fire Department spokesman Michael Hunt said.
Hunt told KALW the fire broke out inside an RV parked outside the gates of the encampment.
Power lines fell across Wood Street and people were advised to avoid the area.
Black smoke could be seen through much of West Oakland after the fire was reported.
The Fire Department wrote on Twitter that the incident was under control as of 1:11 p.m. and several crews were being released from the scene. No other information about the fire was immediately available.
