SALT LAKE CITY - A rare freezing rain caused major havoc in Salt Lake City Thursday, creating sheets of ice on roads, sidewalks and airport runways.

The Salt Lake City International Airport was closed for about three hours, delaying hundreds of passengers. The closure came after a Frontier Airlines plane landing from Denver slid on a patch of ice while on the runway. Nobody was injured.

Morning commutes were brought to a crawl by the icy conditions, which caused dozens of accidents that closed lanes. Utah Highway Patrol called in off-duty officers to deal with all the accidents.

In downtown Salt Lake City and at the University of Utah, people walked gingerly to avoid falling on the ice. At the university library, frozen pipe burst led to a temporarily evacuation.

Freezing rain is uncommon in Salt Lake City. Thursday marked just the 10th time there's been measurable frozen rain at the airport since 1940, said Monica Traphagan, a National Weather Service meteorologist in Salt Lake City.

The amount of freezing rain at the airport is the most since Dec. 31, 1983, Traphagan said. The effect is caused by precipitation that begins as rain in the warmer upper atmosphere but freezes when it hits the valley floor that is below freezing, she said. The inversion effect - which causes the Salt Lake City metro area to have some of the country's unhealthiest air during the winter - keeps cold air trapped in the valley.

The forecast doesn't call for any more problematic freezing rain in the coming days, Traphagan said - just regular rain and snow.

At the Salt Lake City International Airport - a hub for Delta Air Lines - numerous flights were cancelled and many others delayed though exact figures were unavailable.

The first of three runways was reopened at 12:45 p.m. and the other two were opened in the mid-afternoon and early evening, airport spokeswoman Barbara Gann said. Delays were still expected through the night.

The Frontier plane landed safely at 9:30 a.m. and slid on a patch of ice while turning to the taxiway, Frontier Airlines spokeswoman Kate O'Malley said. None of the 139 passengers on the flight from Denver was injured and the airplane never left the pavement, she said.

It's unknown how many airlines have been affected. Delta Air Lines and seven other airlines run flights there. The airport is located five miles northwest of downtown Salt Lake City. The airport has two terminals, five concourses and 83 gates.

There were 188 crashes reported in the Salt Lake City metro area Thursday, said Cpt. Todd Johnson of the Utah Highway Patrol. Nine of those were slide-offs.

"That's an enormous amount of crashes to be investigating," Johnson said.

Twenty-seven people were hurt - including three highway troopers - but none suffered major injuries. The freezing rain conditions are very rare in northern Utah, Johnson said.

"In my 22 years on the road, I can't remember anything like this," he said.

At the University of Utah, a frozen pipe burst in the library forcing a 45-minute evacuation, university spokesman Keith Sterling said. The pipe burst in an employee staff area, causing carpet damage. No books were damaged, he said.