A thick fog rolled down the second floor of Pioneer Hall on the last day of spring quarter classes after a student staged a prank with 200 pounds of dry ice.
According to police reports, College of Liberal Arts sophomore Waris Syed admitted to the prank after authorities questioned him. They later charged him with disorderly conduct.
On June 5, Syed filled bathtubs with containers of dry ice and rigged fans from nearby dorm rooms, blowing smoke throughout the floor, according to the report. He could not be reached for comment.
Dry ice, carbon dioxide frozen at 109 degrees below zero, emits foggy vapor when it comes in contact with water.
Ralph Rickgarn, executive assistant for Housing and Residential Life, said the fog set off fire alarms.
“It created a bit of a ruckus,” Rickgarn said.
Two hundred pounds of dry ice can cost more than $160, said a spokesperson for the Ace Ice Co. in Minneapolis. She also said if the fog becomes thick enough, individuals risk suffocation. Police reported no injuries.
Officials at Pioneer declined to comment on the incident.

In other police news:
ù A fight nearly broke out between two University students early Saturday morning on fraternity row.
According to police, two members of Phi Kappa Psi allegedly were vandalizing trees along University Avenue when members of the Lodge fraternity approached them.
Police arrived to the scene to break up what, according to their reports, was a fight. The incident occurred on the property of Phi Kappa Psi, located on the 1600 block of University Avenue.
Minneapolis Police charged Nicholas Schultz and Jason Hennessy with disorderly conduct.
Schultz is a member of Phi Kappa Psi; Hennessy belongs to the Lodge fraternity.
Hennessy said two students from Phi Kappa Psi did damage to at least five trees along University Avenue and to bushes on the Lodge property. Police confiscated a large flashlight and a wooden club at the scene.
“It was a dumb prank,” Hennessy said. He said he believes the incident was not a fight.
Schultz could not be reached for comment.
Lodge members approached the Phi Kappa Psi property, and at that point members of the two fraternities exchanged words.
“It was just a big misunderstanding,” Hennessy said.
The two students continued to verbally harass one another after officers physically separated them, according to the report.
Members of Phi Kappa Psi declined to comment on the conflict.
More than10 students from nearby fraternities watched the altercation brew between Schultz and Hennessy. But several students in neighboring fraternities said on Tuesday they did not know about the incident.

ù Environmental Health officials ordered staff at Middlebrook Hall to evacuate the premises Monday morning after a chemical mixture produced a strange odor.
Reports of the suspicious smell prompted health officials to flush the area with water.
A member of the Middlebrook cleaning staff mixed bleach and another cleaning chemical together in a drainage trough. The two cleaning solutions produced a “foamy, foul odor,” according to police reports.
Police reported no property damage or injuries.
Middlebrook Hall staff could not be reached for comment.

ù An unidentified woman reported damage to her vehicle June 4 and 5 in a parking lot located adjacent to Middlebrook Hall.
The woman alleged that someone littered her car with wet toilet paper, hamburger buns, trash and other food items. She could not be reached for comment.
The case is pending and police have no suspects.