Lt. John MacNicholl has been placed on leave, Fire Chief Brian Rooney said, following an incident as firefighters battled a March 1 fire at a Laurel Avenue rooming house.

The details of the dispute are under investigation, Rooney said, refusing to elaborate.

The chief identified the captain as Ivan Fossesigurani, who remains on the job.

But the heads of two city groups of black firefighters claim MacNicholl, who is white, shoved Fossesigurani, who is Hispanic. The two group leaders, who are both black, are retired city firefighters.

MacNicholl did not return calls seeking comment.

"This is the worst incident to ever happen in the history of the Bridgeport Fire Department," said Donald Day, president of the International Association of Black Professional Fire Fighters, Northeast Region.

"This is violence in the workplace and the workplace was in a dangerous environment. This act is a total breakdown of the command structure," said Ron Mackey, president of the Firebird Society of Bridgeport, another group of black firefighters.

Compounding the controversy, MacNicholl is president of the Bridgeport Firefighters for Merit Employment, a group predominantly made up of white firefighters.

The Firebirds, the Black Firefighters and the Bridgeport Hispanic Firefighters Association contend the BFME is racist.

BFME officials have repeatedly denied those allegations. The group's stated goal is to uphold the city's civil service system regarding promotion and hiring. Firefighter Robert Whitbread, president of the Bridgeport Fire Fighters Association Local 834, declined to comment on the incident. The case did not come up for review at Wednesday's meeting of the Board of Fire Commissioners, which can issue discipline.

Aaron Leo, who covers regional issues, can be reached at 330-6222.