By Greg Argos

NORTH WILDWOOD, N.J. (CBS) — Tragedy has struck at the Jersey Shore. A Berks County mother drowned trying to rescue her three children from the rough waters.

It happened Tuesday afternoon at the 18th Street beach in North Wildwood. The family was there on vacation.

North Wildwood Fire Chief Dom McClain says 911 operators dispatched first responders for a water rescue around 3 p.m. Tuesday.

Cellphone video shows the large emergency response, behind a backdrop of cloudy skies and dangerous, choppy surf.

“Five cop cars, two rescue cars and a whole bunch of people running toward the beach,” witness Jonathan Selepak said.

Witnesses Jonathan and Stacey Selepak shot the video as first responders tried saving the life of a 49-year-old mother of five.

“I just saw them all converge into one area,” Jonathan Selepak said.

The fire chief says the mom entered the rough water to help her 8 and 10-year-old sons, who had been pulled out too far. Her 19-year-old daughter also entered the ocean to help.

The North Wildwood fire chief says rescue crews arrived within three minutes of the 911 call, but it was simply too late. The mother of five was found some 150 yards out according to the chief, floating facedown in the water.

“I saw just the head bobbing up and down because so many people were there. I knew they were doing CPR,” Jonathan Selepak said.

The mother was rushed to a nearby hospital where she was pronounced dead around 5 p.m.

The fire chief says her two other children and husband were unaware of what initially happened since they were at their nearby Montego Bay Hotel. But the mother, who first responders say is from Wernersville, Pennsylvania likely saved her sons.

The boys and the 19-year-old daughter are expected to be OK.

“That’s the way life works unfortunately and since the kids were saved, that’s wonderful, but it’s unfortunate the mother has had to pass,” Jonathan Selepak said.