Dominique Lafleur, 23, a caseworker with the D.C. Department of Human Services, practices lifesaving skills during the class. (Hamil R. Harris/The Washington Post)

The mayor’s briefing room in the John A. Wilson Building was filled with District workers diligently practicing CPR on plastic mannequins, but Janis Hazel didn’t crack a smile.

As participants in the Red Cross certification class practiced their chest compressions in a joyful rhythm, Hazel mentally returned to the floor of a mini-mart in her home town of Detroit on the day she rushed to the aid of a man who had been shot in a store robbery.

“The person had been shot in the abdomen, and I remember applying direct pressure until help arrived,” said Hazel, the spokeswoman for Serve DC — The Mayor’s Office on Volunteerism. The agency has embarked upon a mission to train resident “first responders” in first aid and CPR as part of the city’s ongoing Community Emergency Response Team (CERT) program.

In 2012, more than 600 District residents were trained to be part of the city’s initial CERT effort, Hazel said. Serve DC has also provided emergency preparedness education to more than 1,000 young people from 15 public and public charter schools and seven outside organizations.

Mayor Muriel E. Bowser (D) said the free CERT training will enable the city’s residents to “act in case of emergencies to save a life before first responders arrive on the scene.”

Porsche Fikes, 29, who was among the city employees taking part in the CPR training session, echoed that statement. “I want to be able to save a life if I am in that situation,” she said.

In addition to its adult program, the agency offers the “Commander Ready” program to train children in the fourth and fifth grades in emergency preparedness. The interactive, four-session program is offered after school and taught by elementary school teachers.

The need for more widespread CPR and first aid training was underscored this summer when the family of a 77-year-old District man who suffered a fatal heart attack across the street from a fire station in Northeast Washington filed a $7.7 million wrongful-death lawsuit against the District, alleging that Medric “Cecil” Mills Jr. could have been saved if firefighters had responded to bystanders who asked them to help.

“The city needs to be held accountable,” Medric Mills III said during a news conference last month to announce the lawsuit.

The seven-count complaint stems from the Jan. 25, 2014, incident, in which Mills collapsed on Rhode Island Avenue NE. Bystanders who rushed to the fire station to get help were turned away and wrongly told that no response could be launched until someone called 911, the suit said. A passing ambulance stopped to help Mills, but he later died.

The D.C. government launched its latest CERT initiative last month. Since June, more than 1,140 people have been trained, including 570 city residents, 151 District government employees and 300 elementary school students who are part of the Commander Ready program.

Nancy Warneke, an instructor with the American Red Cross, said its CPR and first aid training program is invaluable. “You just never know where you will be in life — whether it’s family, community or workplace — when someone has an emergency,” she said. “It’s just an awful feeling to see somebody go down and have the helpless feeling of not being able to help somebody.”

Dominique Lafleur, 23, a caseworker for the D.C. Department of Human Services, was among the District workers getting their CPR certificates at the Wilson Building last week. Lafleur said that she decided to take the class because she wanted to improve her skill set and be prepared to help people she encounters on the job.

“I work in the community and you come across different types of people and sometimes they need help,” Lafleur said. “You just never know when someone will need your help.”

Participant Sam Woods, 22, agreed. “It’s just a good idea,” he said. “It’s better to be trained to do something and not be needed than to not be trained, and people need help.”