The roll call room in the city's Western District police station seems more like a memorial than a meeting place -- one of its walls is covered by brass plaques dedicated to the memory of officers killed on some of Baltimore's roughest streets.

Yesterday, police officials added another plaque -- the 15th -- to the wall of honor. This one was for Officer Crystal D. Sheffield, 35, who died in a car accident in August while responding to a colleague's call for help.

Calling Sheffield a hero, Mayor Martin O'Malley and Police Commissioner Edward T. Norris said the officer and others were responsible for drops in violent crime citywide.

"She chose not to do the thing that was easy," O'Malley said. "She chose to do something inherently unsafe."

"Police are very special people, in my opinion," Norris told more than 150 officers, firefighters and friends who crowded into the roll call room for the hourlong ceremony. "They put their lives on the line for people they don't know or barely know."

After prayers and two songs by the Police Department's choir, Norris and Maj. Antonio Williams, the Western District's commander, unveiled the plaque that recognizes Sheffield's "honorable and faithful service."

Sheffield, the city's first female officer to die in the line of duty, was responding to a call for help when her patrol car was hit by another police car racing to the same incident. Her husband, William Andre Sheffield, and 11-year-old son, Darian, attended yesterday's ceremony.

Police said the plaques should serve as reminders to themselves and the public that officers face many dangers on the streets.

"In law enforcement, there is a whole lot we cannot control," Gary McLhinney, president of the Fraternal Order of Police Lodge 3, told the crowd. "We can't control the next call or how our day will go. But we control how we remember our fallen brothers and sisters."