Update 1:25 p.m.: West Conshohocken police at the scene said the rescue has been completed. According to police, three people and a dog in a pontoon boat got caught up on some rocks in the former vicinity of the Plymouth Dam. 

The boat was dislodged and the three boaters reportedly continued their trip down the river. West Conshohocken police chief Michael Sinclair said further details would be pending a report.

Initial story below.

Multiple emergency responder units have been dispatched to a boat ramp area along the Schuylkill River in West Conshohocken following a report that three people are trapped on the remnants of the former Plymouth dam.

The Schuykill Sojourn boating event is in its final day on that segment of the river, but there's no indication thus far that this rescue is connected to that activity.

The Plymouth dam was built in the mid-19th century. It fell into disuse and poor repair and was removed in 2009.

Editor Kyle Bagenstose is en route to the scene. We'll have additional updates as they become available.