VA Secretary Robert Wilkie said patient care was not affected by the blast on the West Haven campus of the VA Connecticut Healthcare System.
"Emergency personnel are on the scene,” Wilkie said in a statement. “Our prayers are with the families of the victims of this explosion.”
Max Reiss, a spokesman for Gov. Ned Lamont said a third person was missing.
West Haven firefighters described it as a “steam explosion” at a facilities building a short distance from the hospital, their union said in a Facebook post.
Gov. Ned Lamont, a Democrat, said state emergency management officials will provide as much aid as necessary to conduct an investigation. Early indications point to a steam pipe, he said.
"This is a heartbreaking tragedy, and I have instructed our state agencies to provide full resources as the response and investigation continues,” Lamont said.
One of the people who died was a VA employee and the other was a contractor, said U.S. Sen. Richard Blumenthal, a Connecticut Democrat.
“This kind of explosion may have been the result of a mechanical failure or a mistake on the part of someone at the VA. We have no firm facts as yet," Blumenthal said.
The contractor who died worked for Mulvaney Mechanical, based in Danbury, Connecticut, said company Vice President Charles Brough. He said he did not have information about the work being done, and the company did not release the contractor's name.
The area of the campus where the blast happened was taped off by late Friday morning, but people were being allowed to enter and exit the main hospital building.
The federal Occupational Safety and Health Administration is looking into what happened, spokesperson Jim Lally said.
Associated Press writers Dave Collins in Hartford and Michael Balsamo in Washington contributed to this report.