The Missoula County Sheriff?s Department called off the search for the University of Montana student who went missing on the Clark Fork River Wednesday night.

Witnesses watched as the 19-year-old was sucked under after he reportedly jumped off the Madison Street bridge near the university around 6:20 p.m.

Search crews from the Missoula County Sheriff's Department and the Missoula Fire Department scoured the area until sunset Wednesday, and were back in the water early Thursday morning.

They covered an area stretching 15 miles from Madison Street to Council Grove State Park.

Rising waters by the end of the day hampered efforts and crews believe they exhausted all resources to find the body.

Almost 24 hours after he went missing, officials said there was still no sign of the teenager, and after 3 o'clock Wednesday, officials called off the search.

"We're supporters of recreating - that's why we live here in Montana,? said Missoula County Sheriff?s Detective Jason Johnson. ?We just want people to do it safely. The great warm weather that we've had lately brings recreaters to the water, and that's great, we just want people to think about the risks that they're taking."

Witnesses said the missing student wasn't the only one who jumped in the water. He was seen swimming in the river earlier with a woman, who reportedly jumped off the bridge just before he did. Witness Danielle Chesley said the missing teen seemed scared, but she said the girl coaxed him into jumping.

"Somebody was able to bring him to that point, where he was ignoring his own feelings,? said Chesley. ?He knew he didn't want to jump in this water, and she convinced him somehow that it was going to be okay."

Missoula police say they've talked to the woman about what happened, but at this point they say they aren't investigating any foul play. Police haven't released the woman?s name, or the victims, but they stress that western Montana waterways are high and extremely dangerous, and they ask people to stay out.