http://www.channel3000.com/news/5680505/detail.html MADISON, Wis. -- Two people were taken to the hospital on Tuesday after a manhole cover blew through the floor of a Metro bus at Badger Road and Perry Street in Madison. Officials at the scene are calling it a bizarre accident that happened as the bus rolled over a manhole cover. The cover blew through the floor and left a gaping hole. The bus came down so hard that the front windshield cracked, WISC-TV reported. The cover sent the bus up in the air and pushed it 200 feet, WISC-TV reported. The bus driver told WISC-TV that it made a loud crashing noise. About 25 people were on board on the bus, and two were taken to a local hospital. One complained of whiplash injuries. The other wanted to be checked out for possible injuries. Others were taken to the south transfer point to catch other buses. Officials said that there was no explosion, and that they believe the bus flipped the manhole cover, WISC-TV reported. Madison police called on several agencies as they investigated the accident to determine its cause. "We contacted MG & E and had gas test and electrical test," said Madison police Sgt. Chris Paulson. "We also had the Dane County bomb squad come down to make sure there's nothing unusual. Anything unusual has been ruled out." Even federal investigators were called on the scene, and ATF officials ruled out any type of explosion. Authorities determined the cause to be mechanical failure.