MANKATO — A planned implosion of a high-rise dormitory at Minnesota State University-Mankato has gone off smoothly.

The 12-story towers of the Gage Residence Community were safely imploded Saturday.

Hundreds of spectators gathered to watch the buildings come down. First an announcer counted down, and then a series of blasts could be heard. At first nothing happened, but a second or two later the towers began to collapse inward.

In 12 seconds the building was reduced to rubble, and a huge dust plume expanded in a cloud.

The site will be redeveloped for parking. Two new buildings have already replaced the dorm after the university decided it was cheaper to build new housing than fix up the old complex.