The mayor’s office has called upon the city’s firefighters to help prevent neighborhood crime until at least spring 2012, city officials said Wednesday.

For the past three weeks, firefighters have parked their trucks at locations across the District to deter criminals, said Paul Quander, deputy mayor of public safety and justice. Wednesday’s deployment coincided with the first payday for participants of the city’s Summer Youth Employment Program. In past years, youths in the program have been mugged on payday, city officials said.

“You don’t have to wear a badge and uniform and gun to have an impact on safety,” Quander said. “Public safety is not just the responsibility of the police department.”

Quander described the citywide effort as a strategic use of staff to help make communities safer. Firefighters have been asked to dial 911 if they see suspicious activity in their area, he said.

The police and fire departments have identified about a dozen intersections at which firefighters will be posted, according to internal e-mails among city officials obtained by The Washington Post. Officials said in the e-mails that the firefighters should watch out for the safety of the youth employment program participants.

Last year, several youths wearing bright blue “Mayor’s Conservation Corps” T-shirts were mugged on days they were paid, said Neville Waters, a spokesman for the Department of Employment Services, which oversees the program. He said the program’s 14,000 participants each carry a pay card, which can be used to withdraw money from banks and ATMs.

This year, participants no longer sport program T-shirts, which Waters said may have made them targets last year.

Quander said there was one reported mugging of a program participant Wednesday.

Police and fire union officials questioned the decision to deploy the city’s firefighters to street corners, citing training and safety concerns. “My concerns are what role they are to play if they witness a crime,” said Edward Smith, president of the D.C. Firefighters Association. “We respond to violent crimes or medical emergencies, but we wait until police secure the scene — we could potentially be in harm’s way.”

Kristopher Baumann, head of the D.C. police union, criticized the effort as a “dangerous stopgap measure.”

“These guys are being asked to take on a law enforcement role with no training or coordination with the police,” Baumann said. “It’s like asking the police to start fighting fires.”