SIOUX FALLS, S.D. - Thousands of spectators gathered Saturday to watch the demolition of the city's tallest building — but the Zip Feed Mill tower was no pushover.

The 202-foot-tall concrete structure dropped slightly, leaned a little — and stopped. Onlookers at viewing spots all over downtown groaned and gasped — with a few jokes mixed in.

"The leaning tower of Zip," one woman said.

"The building won!" yelled another man, to the cheers of onlookers.

The abandoned feed mill elevator, widely considered the tallest building in South Dakota, was being demolished to make way for office and retail space.

The property owners had turned the event into a fundraiser for the Dakota chapter of the National Multiple Sclerosis Society. Residents bought T-shirts and $1 raffle tickets for the chance to trigger the blast, and stood outside with temperatures in the teens to view the tower's demise.

Crews had drilled holes into the tower's supporting columns and stuffed them with explosives, intending to drop the tower like a falling tree.

However, the rear of the tower was so rotten that it wasn't stiff enough to push over, said Jim Redyke, president of blasting specialist Dykon Explosive Demolition of Tulsa, Okla.

"As the weight was transferred to the back side, it crushed the back walls and it crushed the basement wall," Redyke said. The tower collapsed into the structure's basement and got wedged.

Crews planned to return to knock it down with a crane, but that might not occur until Thursday, said Jeff Hanson, spokesman for the site's co-owners, Raven Industries Inc. and Howalt-McDowell Insurance Inc. Officials and the contractor in charge examined the site and determined the tower would hold, but the site remains fenced off and watched by security guards...