Authorities in central Minnesota and northern Wisconsin are searching for four college-age students after they went missing when returning from bars or late-night parties.

The latest incident involves Josh Guimond, 20, a Saint John’s University junior from Maple Lake, Minn., who witnesses said was last seen about midnight Saturday after he left a party.

Divers Monday searched a lake near where the party was held, but did not find Guimond. The search then utilized a State Patrol helicopter, and authorities on horseback were also dispatched.

In Eau Claire, investigators are clueless as to the whereabouts of University of Wisconsin-Eau Claire student Michael Noll. Noll was last seen leaving a bar late Wednesday on his 22nd birthday.

Friends and family of Noll were encouraged Monday when an elderly resident told police he saw a man matching Noll’s description wandering into a home intoxicated and confused. Police have asked residents to look near their homes or check their houses for any sign of Noll.

Deputy Chief Gary Foster of the Eau Claire Police Department said investigators have no reason to believe foul play was the cause of Noll’s disappearance. They are currently looking along the Chippewa River.

Another student is missing at the University of Minnesota-Twin Cities. Christopher Jenkins, 21, of Eden Prairie, was last seen leaving a Halloween party at the Lone Tree Bar & Grill in Minneapolis. Earlier this week, authorities were searching for Jenkins on the banks of the Mississippi but were unsuccessful in locating him.

The fourth student missing, Erika Marie Dalquist of Brainerd, Minn., disappeared Oct. 30. Police plan an air and ground search for Dalquist, 21, who was last spotted leaving a bar in downtown Brainerd.

Authorities have no reason to believe any of the cases are related, but remain open to the possibility.