ANCHORAGE, Alaska >> A grizzly pounced so furiously on a group of teenagers in the Alaska wilderness that they did not have time to pull out their bear deterrent spray to defend themselves, the father of one of the boys said Monday.

The seven teenagers were in the last leg of a 30-day backcountry education course when they came upon the bear and its cub on Saturday night. The teens at the front of the pack bore the brunt of the attack, authorities said.

They were rescued early Sunday after activating their emergency locator beacon and tending to the wounded.

"They startled this bear," Jon Gottsegen said in a telephone interview from his Denver home, his 17-year-old son Samuel among the four injured teenagers. "It sort of came around a curve."

The bear attacked as they group lined up for a river crossing in the Talkeetna Mountains, north of Anchorage. Those in the back of the line heard the warning, and the two at the front were most seriously injured, authorities said.

"One of the most dangerous things to run into in the woods," said Patricia Allaire, the mother of another injured student, Noah Allaire, 16, of Albuquerque, N.M. She said none of the teens had guns.

The teens were taking part in an outdoor education course from the National Outdoor Leadership School, which leads many such excursions in Alaska and elsewhere.

Another group of seven students and three instructors waited about six miles away for a helicopter hired by the Lander, Wyo.-based NOLS, said Bruce Palmer, a spokesman for the organization.

Palmer said the worst injured with bear bite wounds are Joshua Berg, 17, of New City, N.Y., and Gottsegen. They were being treated at Providence Alaska Medical Center in Anchorage.

Berg was in in serious condition and Gottsegen was upgraded to good from serious, a hospital spokeswoman said.

Gottsegen told Denver’s KMGH-TV that the first person to go around a corner yelled that there was a bear and then started running backward. Then Gottsegen said he looked behind him and saw the bear so he started running.

He said the bear tackled him on the way down on a hill.

"I thought I was going to die when I was being attacked. I was so scared," he said from his hospital bed.

When the bear broke off the attack, the teens activated a personal locator beacon they carried for emergencies, trooper spokeswoman Megan Peters said.

Patricia Allaire said her son tried to activate the beacon, thinking the bear was gone, but then it struck again, thrashing the teen’s head and back, and slightly puncturing a lung.

Noah Allaire was listed in good condition Monday, a hospital spokesman said.

The Rescue Coordination Center operated by the Alaska Air National Guard called troopers around 9:30 p.m. to report the activated signal. A trooper and pilot in a helicopter located the students in a tent shortly before 3 a.m.

They decided the two most seriously injured would need a medical transport aircraft.

The trooper and another student stayed with the badly injured teens for four hours until more rescuers arrived in a specially equipped helicopter, Peters said.

The uninjured student who remained was 16-year-old Samuel Boas of Westport, Conn. The NOLS spokesman, Bruce Palmer, said Boas has training as an emergency medical technician.

Gottsegen said the teens used their survival training, making a bandage out of a garbage bag.

The other students injured were Victor Martin, 18, of Richmond, Calif., who was treated at a hospital for a bite wound above his ankle and then released, according to Palmer.

The teens were in the 24th day of their course when the attack occurred. There was no instructor with them because that far into the course, they’ve learned enough survival skills, Palmer said.

"Our basic goal is that when a student graduates from the NOLS course, they have the experience and background to be able to take other people out into the backcountry," he said. "We’re training people to be outdoor leaders."

Calling out to alert bears of human presence and give animals a chance to flee is among the skills they learn.

"The students say they were" doing that, Palmer said.