MILWAUKEE, Wis. -- A Medical Transport jet from the University Of Michigan crashed into Lake Michigan Monday afternoon.

Police said six people were on board. Coastguard officials said they have found debris from the plane and human remains. Officials said they believe this is a non-survival plane crash.

"Our hearts are broken today," said Mary Sue Coleman, University of Michigan president in a Tuesday morning news conference.

"The condition of the aircraft debris and human remains found indicate a high-speed impact," Capt. Bruce Jones said. "We believe this to have been a non-survivable crash. We offer our greatest sympathies to the families of these victims."

The University of Michigan identified the victims as Bill Serra and Dennis Hoyes, both pilots from Marlin Air; David Ashburn, M.D., Martinus "Martin" Spoor, M.D., Richard Lepensee and Richard Chenault II, both transplant donation specialists.

Marlin Air flies all survival flight airplane missions, according to the University Of Michigan.

The jet took off from Mitchell Airport in Milwaukee, Wisconsin and was bound for Willow Run Airport in Washtenaw County.

According to the University Of Michigan, those on board were returning after procuring organs for a transplant at UM.

"The thoughts of the entire university community are with the families of those involved this evening. We take consolation in the fact that the team was on a mission to help another, " said Darrell A. Campbell M.D., chief of staff of the UM Hospitals and Health Centers. "We vigilantly await the results of the U.S. Coast Guards search."

Campbell said as soon as they received word of the incident, UM contacted the transplant team that had been preparing the patient, and the operation was suspended.

As of Monday night, the patient, according to UM, remained in critical condition. Citing patient confidentiality laws, UM declined to give detailed information. However, sources tell Local 4 News the patient was scheduled to receive a double lung transplant.

Coast Guard Petty Officer David Warfel said the plane took off about 4 p.m., almost immediately reported there was a problem on board, and asked for permission to return to Milwaukee. Warfel said the jet quickly dropped off radar and a witness later told police she saw a 20- to 30-foot high splash after the plane hit the water.

Warfel said the Coast Guard found the plane about 20 minutes later -- about a mile and a half off shore.

Marlin Air works with Southfield-based Toy Air. Bob Page, president of Toy Air, confirmed the jet belonged to his company and was being used by the University of Michigan Survival Flight team. The plane was a Cessna Citation.

"It didn't seem real," Page said. "That type of aircraft is very reliable, very rare to have issues with it. I have met the people at U of M. This is a tragic loss."

The Coast Guard said divers have found pieces of debris and it appears the jet is in an area about 20 feet deep.

There is still no word on what may have caused the jet to crash.

"This is a tremendous blow from which we won't quickly recover," said Dr. Robert Kelch, CEO University of Michigan Health System in a news conference on Tuesday morning.

There will be another briefing at 5:00 p.m.

The National Transportation Safety Board arrived on scene Tuesday. NTSB Senior Air Safety Investigator John Brannen said they listened to audio between the tower and plane and the pilot reported a problem with its trim runaway system. The system controls bank and pitch, but he doesn't know what could have caused the problem.

"We will piece together what we can of the wreckage," Brannen said.

The problem has previously caused accidents, he said. They also planned to look at the aircraft's maintenance records within the next few days.

Milwaukee County Medical Examiner Jeffrey Jentzen said he likely would have to use dental records and DNA to identify the victims.

"A high-speed impact in water causes explosion-type injuries," he said.

There were 55 accidents involving emergency medical services flights -- those carrying patients or organs for transplant -- between January 2002 and January 2005, according to the most recent National Transportation Safety Board study on the issue. The study found several safety problems, including less stringent requirements for EMS flights that did not carry patients.

Stay with Local 4 and ClickOnDetroit.com for more on this developing story.