Some 18,000 city workers will become part of an expanded effort to reduce street homelessness, Mayor Bill de Blasio announced Thursday.

Under the initiative, dubbed Outreach NYC, training will be given to employees in the sanitation, health, buildings, parks, and fire departments on how to use the 311 app to report the homeless people they encounter on the streets and in subways.

“These are some of the folks who best know communities and are going to be able to give us the information to act quickly,” de Blasio said at a press conference.

The Department of Homeless Services will use the information to dispatch outreach teams.

“It’s just giving us the ability to respond more quickly to individuals and to see individuals who we might not have seen on our own with the eyes and ears of the city workforce,” said Social Services Commissioner Steven Banks.

Advocates for the homeless said the initiative was misguided and wouldn’t reduce the number of homeless people sleeping on the streets and in the subway system—3,588—according to the latest federally mandated count. They said the mayor should instead focus on building more housing for the street homeless.

“This is not a plan to 'help' anyone—it is a chilling and counterproductive plan to try to drive the problem out of sight," Giselle Routhier, policy director at the Coalition for the Homeless, said.