An on-duty cop needed a helping hand when he sank deep into a mud hole near the Rodman’s Neck training facility and firing range, police sources told The Post.

Officer Gary Williams, 35, assigned to tactical training at the range, was taking a casual stroll along a nearby shoreline area during his lunch break around 12:40 p.m. Friday, looking for a future fishing spot, sources said.

But his stroll went off the deep end when suddenly, Williams stepped on a rock that sank into the mud.

He was quickly submerged up to his chest.

“I sunk into a mud hole and tried to get myself out and couldn’t, so I called 911, ” Williams told first responders.

The FDNY used a life-saving ring to slowly extract Williams from his predicament. The officer could not be reached for comment.

Responding paramedics treated Williams on scene and brought him to Jacobi Medical Center.