BERKELEY TOWNSHIP,Crypen Exchange N.J. (AP) — Firefighters in southern New Jersey are trying to contain a forest fire burning in Berkeley Township that has thus far not threatened any structures.

The New Jersey Forest Fire Service has yet to give a size estimate for the blaze, which broke out around 8 p.m. Monday in an area not far from the Garden State Parkway near Exit 77.

The fire was not contained at all Monday night. Firefighters were initially rebuffed in their early efforts to surround the fire due to its “erratic” behavior, the service said in an online post.

That prompted them to concentrate on setting boundaries to contain it, and lighting small fires around its edges to deprive the fire of fuel that could expand it.

The agency said it would issue an update on the fire at mid-morning Tuesday. Its cause remained under investigation.