A Massachusetts boy fell off a boat in Lake Winnipesaukee and was struck by its propeller Saturday, suffering “noticeable blood loss” and multiple lacerations below the left knee, state police said.

The 10-year-old boy from Acton was in stable condition at Lakes Region General Hospital in Laconia and was being admitted to undergo surgery, police said.

When Marine Patrol arrived in the area of Eagle Island, the boy’s legs were wrapped in towels. The victim and his mother were transported by Marine Patrol to the Weirs town docks where an ambulance was waiting.

Four adults and four children were on board the vessel; the children were swimming when the boat drifted into shallow water, police said. Everyone reboarded the vessel, so the boat could navigate into deeper water. The operator, Robert S. Wood, 70, also of Acton, shifted the vessel into reverse and while backing up encountered numerous large boat wakes that sloshed over the swim platform. This shook the boat, causing the victim, who was seated on the transom cushion, to lose his balance and fall over backwards, police said.. His legs then came in contact with the propeller.

At least one adult passenger jumped into the water assisting the victim back onto the boat.

The accident occurred between Bear and Mark Islands

Alcohol and drugs do not appear to be a factor in this accident.