St. Paul Police spent Sunday searching by ground and air for a missing University of St. Thomas student.

Police said 18-year-old Dan Zamlen was last seen leaving a party around 3 a.m. Sunday.

He called a friend to say he was walking along the Mississippi River. But that call ended abruptly. The last thing his friend said she heard was, "Help, Oh my god."

Investigators said Zamlen has type I diabetes and the longer he's without insulin the worse this situation could be.

Investigators said they did find one set of footprints that could match his size that were facing away from the river, towards the road, but are not saying much more about the investigation.

Zamlen's 19th birthday is just three days away.

"You know you always see it on the news, college kid missing, or some little kid, you feel bad for the family, this is the last thing I ever thought I'd deal with," said his younger sister, Andrea Zamlen. "He's Type I diabetic. He was drinking. He could be at a low. He has an Omni Pod attached to his body but he needs to be coherent enough to type it all in."

Police said Zamlen went to a party Saturday night on St. Clair Avenue. His sister told 5 EYEWITNESS NEWS the St. Thomas freshman left on his own. She said something made him angry and he wanted to cool off. She said he'd been drinking, but would never wander for so long.

"This is not like Dan. There's something wrong if he's not coming home or answering his phone," said Andrea Zamlen.

The State Patrol helicopter made low passes along the river searching for any sign of him Sunday. Firefighters climbed down the Mississippi bank. Friends are showing pictures and posting flyers hoping to find Zamlen.

Zamlen is from Eveleth and lives in Brady Hall. He is described as 6 feet tall, 175 pounds with blond hair and blue eyes. He was last seen wearing a blue jacket and jeans.

Anyone with information is asked to call St. Paul Police or the University of St. Thomas Public Safety Department at (651) 962-5555.