DURHAM -- As students and faculty returned to the Levine Science Research Center, investigators are still trying to figure out exactly how a Duke University employee died.

Rayford Cofer, 63, of Franklinton, died Wednesday afternoon when a steam vent ruptured in a school science building. He was working in a mechanical room in the basement of the Levine Science Research Center when the steam line exploded.

"We're confident the building is safe," said Kemel Dawkins, vice president of campus services.

University officials won't say how Cofer died or exactly what he was doing when he died.

"We know that there was a team working in the building at the time. We're making assessments of all the things they were doing," said Dawkins.

The rupture triggered sprinklers, and then the basement flooded.

"Most of the water is gone... enough was removed that we could bring the power back on," explained Dawkins.

Duke University is conducting its own investigation as well as the North Carolina Department of Labor’s Division of Occupational Safety and Health.

"Well, obviously we're learning more every moment, but we're still far away from drawing any conclusions from this," said Dawkins.

The Department of Labor said its Division of Occupational Safety and Health has never inspected the Levine building.

However, in 2003, it did cite Duke University for two "non-serious" citations in another building.

One was for violating a safety gear requirement and the other for improper hazardous chemical training.

The focus now, though, is what went wrong in Levine.

"We will be reviewing first this incident, and from that, any conclusions that we draw, obviously will lead to other assessments," said Dawkins.

Meanwhile, the campus remembers the man who the university honored twice for his hard work.

"Many of Ray's colleagues and friends were also very saddened," said Dawkins.

"I just heard the alarm and all the people rushing out," Duke graduate student Trang Pham said. She works in the building every day.

Pham and other students and staff in the building didn't have much time to think Wednesday after the accident happened.

"A professor told me, 'You have to go out,'" she said.

Some people in the building heard explosions, and others felt the building shake. Emergency crews had a hard time getting into the maintenance room to help Cofer.

"After the incident, the room was very, very hot. There had been a release of water. The space in that portion of the building is very cramped," said Dawkins.

"It's obviously just a horrible tragedy and we're very sad. We're sad for the family," said John Burness with Duke Public Affairs.

The 341,000-square-foot facility is a multipurpose center housing classrooms, laboratory space and offices shared by the Nicholas School of the Environment, Pratt School of Engineering, the Center for Cognitive Neuroscience and Developmental and the departments of Computer Science, Pharmacology and Cancer Biology and Cell and Molecular Biology.

No experiments or lab work are to blame for the explosion. The steam lines are used to heat and cool the building.

Students like Phan say they will continue even after the explosion.

"We have to work here and we have to trust the people here," she said.

The school said Cofer was a respected and honored employee in Duke's Facilities Management Department. He began work there in 2001 and was a two-time meritorious service award winner, one of the top employee honors at Duke.