Update, 4:45 p.m. Monday:

A second West Valley High School student was released from the hospital on Sunday, said Sharice Walker, public relations director at Fairbanks North Star Borough School District.

As of Monday afternoon, one student remained at the hospital, she said.

Original story:

Two Fairbanks high school students who were sent to the hospital after participating in a football team-building exercise Friday night at a university pool remained “under medical observation but were alert and communicative” Sunday, according to a school district spokeswoman.

One other student was released Saturday from the hospital.

The three West Valley High School students were “interested in trying out for football,” according to Sharice Walker, public relations director at Fairbanks North Star Borough School District. They were participating in a team-building exercise at the University of Alaska Fairbanks pool during an “optional preseason activity” hosted by football coaching staff, Walker said.

During the exercise, three students became submerged in the water and were then “pulled from the pool and transported via ambulance to the hospital,” Walker said.

“It is a serious situation and we are just beginning our investigation of the incident,” Walker said.

Seven members of the coaching staff and a lifeguard were present at the time, supervising about 40 students, Walker said. She said it’s not yet known if additional adults were present.

Witnesses said students were treading water in the deep end of the pool when “at least one of them” sank to the bottom, UAF spokeswoman Marmian Grimes said Saturday.

According to a written statement from the Fairbanks North Star Borough School District on Saturday, all West Valley High School football preseason activities had been suspended.