A 37-year-old man who was naked, lying face down in the mud by Agassiz Road, and screaming, was helped up by EMS and is being evaluated, Boston Police Spokesman Steve MacDonald said. 

"It was an unusual incident," MacDonald said. "...He appeared to firefighters to be under the influenced of something."

Boston Police responded at 4:58 p.m. to 59 The Fenway for reports of screams in the area. The man was not in the water, and was in no obvious danger.