NEW YORK — Five kayakers were injured Tuesday when they were struck by a ferry departing a Manhattan pier and tossed into the Hudson River, police said.

It happened just before 6 p.m. near Pier 79 as a group of 10 people in eight kayaks were paddling down the river on a brief excursion, New York Police Department Inspector David Driscoll said.

At least two of the kayaks were struck by a NY Waterway ferry.

“The kayakers were all over the place,” said NYPD Officer Tommy Le.

The most seriously injured, an employee of the Manhattan Kayak Company, had his arm partly severed.

“He was lying on top of the kayak and there was a pool of blood,” said Le, who applied a tourniquet to stop the bleeding.

Authorities credited Le’s quick action with possibly saving the man’s life. The kayaker was listed in stable condition at a hospital.

The others suffered minor shoulder, back and head injuries, Driscoll said.

Authorities were investigating whether the sunset or glare was a factor in the accident and what navigation rules applied.

Nevertheless, “both parties are responsible for staying out of each other’s way,” added Driscoll, who said the ferry captain tested negative for drugs and alcohol.

A spokesman for NY Waterway said it was cooperating with police and the Coast Guard, which has taken over the investigation. The private ferry line transports passengers to various locations, many along the Hudson River in New York and New Jersey.

A message left with the Manhattan Kayak Company was not immediately returned.