Police confirmed that a standoff began at about 6:45 a.m. and was still under way as of shortly before 10 a.m., but were not immediately releasing additional information about the situation.
The employee, who did not want to be named, said the standoff is taking place in an area near the marina's launch ramp.
The employee said he didn't know whether the man was armed.
Other than the area near the launch ramp, the rest of the marina remains open, he said.
