Two factory workers died early today after an explosion hurled them into a tank of caustic sulfuric acid at a Howard County industrial plant, fire officials said.

The victims, identified by authorities as William A. Caldwell III, 30, of Arbutus, Md., and Donald L. Severe Jr., 28, of Baltimore, were on a catwalk on top of the tank when the blast occurred at 11:39 p.m. Wednesday at Chesapeake Finished Metals Inc. in Elkridge, Md., plant officials said.

No other employe was injured, but two firefighters, Capt. John Schulte and Dan Brown, received first-degree acid burns during rescue efforts, said Edgar G. Shilling, a Howard County Fire Department spokesman.

The cause of the blast was unknown yesterday. Investigators could only speculate that gas may have ignited or that the tank could have been over-pressurized. The company electroplates metal products.

Raymond E. Lloyd, an assistant commissioner with the Maryland Occupational, Safety and Health Administration, said the inquiry by his office was stymied by "disarray" at the plant.

"It's one of those situations where we don't have a lot to go on," Lloyd said. "We haven't even been able to get in to the blast site yet."

A spokesman for the company issued a short statement saying there had been "an apparent explosion of a plating tank," but declined further comment.

Firefighters who arrived at 11:45 p.m. discovered the men floating in 3 to 5 feet of sulfuric acid solution in the 20-foot-deep tank, Shilling said.

Schulte was burned on his arms and legs when he was lowered into the tank by a hoist to retrieve Caldwell, who died later at Baltimore's shock trauma unit. Severe was pronounced dead at the scene, Schilling said.

The bodies were sent to Baltimore for autopsies.