MADISON, Wis. -- A preliminary report released Wednesday offered no cause for why a University of Wisconsin Hospital Med Flight helicopter crash two weeks ago, killing three crew members.

SLIDESHOW: See Photos Of Med Flight Helicopter Crash Site | SLIDESHOW: See Photos Of Med Flight Victims

The National Transportation Safety Board issued the report Wednesday, but it offered few new details. The report indicated that the helicopter collided with trees and terrain southeast of La Crosse on its way back to Madison.

The report said that the flight was conducted in accordance with federal aviation regulations, and gives no indication that there were any violations with the flight plan or equipment on board.

According to the report, the helicopter crew left La Crosse Airport 10:30 p.m. on May 10 after refueling. Soon after, local authorities received a 911 call from a resident stating that they heard what they thought was an aircraft crash. At 11:04 p.m., UW Hospital notified local authorities that the aircraft was missing. A search ensued, and the crash site was located at about 9:00 a.m. on May 11.

The three victims -- Dr. Darren Bean, a physician, Mark Coyne, a registered nurse, and Steve Lipperer, the pilot -- were all killed in the crash. All three lived in Madison.

The crash report said that calm winds, a visibility of eight miles, and light rain at the time of the crash. An employee who fueled the Med Flight helicopter before it took off reported moderate rain and fair visibility.

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To read the entire NTSB crash report, click here