Baltimore fire officials suspended emergency medical training and locked down an instructional facility Monday after revelations that some student firefighters had cheated on a state licensing exam, officials said.

"This is a serious mistake that tarnishes the reputation of the hundreds of professional and dedicated men and women who work so hard for us," Fire Chief James S. Clack said in a statement.

The state agency that oversees paramedics and emergency medical technicians notified the Fire Department last week that it had determined that students cheated on the practical segment of a test administered June 14.

The 20 students in the class under investigation make up only the second class to begin at the fire academy in more than a year. The department had ceased hiring until last fall because of city budget cuts; the new hires were expected to help relieve staffing pressures in the department, which has closed fire companies on a rolling basis for years to save money.

"We don't have much detail on this incident, but we will find out the who, what and when," Clack said at an afternoon news conference.

Clack noted that it was alarming that the alleged cheating had occurred during the practical segment of the test, in which students are required to provide a mock examination and treatment.

"The student has to size up the scene, talk to the victim, if conscious, and take appropriate action," Clack said. "This test shows their skills beyond the classroom and the books. If they can't apply those skills, the knowledge is of no use to them."

The students had obtained details about the mock victim and the scenario, but it is unclear how many students were involved. A spokesman for Mayor Stephanie Rawlings-Blake said she would wait until the investigation had concluded to determine if instructors or students should be dismissed.

Rawlings-Blake "is very troubled by the allegations and supports Chief Clack's efforts to fully investigate the matter while suspending the program," spokesman Ryan O'Doherty said in a statement.

"This type of behavior will not be tolerated and both the mayor and Chief Clack are committed to restoring the integrity of the testing process," he said.

Two concurrent fire academy classes were not implicated in the cheating scandal.

Baltimore Fire Marshal Raymond C. O'Brocki is supervising the department's investigation at Clack's request. O'Brocki said he locked down the emergency medical training facility on Pimlico Road on Monday.

Classes were suspended at that facility, although firefighting classes at Pulaski Highway are continuing, O'Brocki said.

"We didn't want to have EMS training while this was going on, in case any corrective action needed to be taken," he said.

O'Brocki said he had begun "securing documents, gathering the names of people we need to interview and gathering test booklets." The investigation is expected to take two weeks, Clack said.

City fire officials will use the state investigation as a "starting point," but will also examine the results of previous classes and current firefighters who have recently undergone recertification, O'Brocki said.

"We want to interview not just current academy staff, but also former academy staff," he said. "I don't have any expectation that we will find any more improprieties, but I don't have any expectation that we won't find any."

Twenty students who took the test on June 14 will be required to repeat it, Clack said. The class is expected to graduate in August, and there is no indication that the incident would delay the class' graduation, a Fire Department spokesman said.

The test includes 100 written questions and practical tests involving medical concerns, trauma and resuscitation, said Dr. Robert Bass, executive director of the Maryland Institute for Emergency Medical Services Systems.