OAKLAND — Oakland opened the gates to its first “safe haven” city-sanctioned and operated homeless encampment Monday.

The encampment occupies what was an empty lot between Sixth and Brush streets and Seventh and Castro streets. It features 20 modular units similar to “Tuff Sheds,” designed to house 40 people for up to six months at a time. The encampment will offer a variety of services aimed at getting homeless people into more permanent housing.

City officials have been working for months to get the program up and running as part of a broader effort to reduce Oakland’s unsheltered population.

“We’re very excited that we are starting to put up this Tuff Shed shelter, but let’s be clear, this is not a permanent solution; this is a right-now intervention,” Oakland Mayor Libby Schaaf said at a news conference.

The sheds each house two people and a couple of them are used to store occupants’ possessions, Oakland Assistant City Administrator Joe DeVries said. A site manager and a case manager both have offices at the site, and security guards patrol at night.

Portable toilets and hand-washing stations serve the sheds’ occupants; the city has contracted with the nonprofit Lava Mae, of San Francisco, to bring mobile shower facilities there once a week.

Electricity isn’t available in the sheds, DeVries said, but the site manager and case manager’s offices will have electricity if occupants need to charge their cellphones or otherwise use the power, he said.

A dog run also has been set up.

The lot is being paid for by Pacific Gas and Electric Co., which had originally rented it from a private owner to stage equipment. PG&E decided to let the city use the land instead and will eat the cost, DeVries said.

The sheds were purchased with donations from the Oakland Metropolitan Chamber of Commerce and Sutter Health; the Oakland Builders Alliance donated materials and labor.

“Oaklanders showed up the way Oaklanders do: with compassion,” Schaaf said.

Between money from the city’s budget and outside donations, the site has about $550,000 to work with. That will pay for the wrap-around services, security and others services.

Safe Haven residents are expected to follow the site’s rules, which prohibit weapons, violence and using drugs in the open. They will receive reports every 30 days on their progress in finding stable housing.

If they don’t follow the rules, DeVries said, they could be expelled.

“We have to assume as much good as we can; these are people who need shelter, and they’re in tough shape,” DeVries said. “We have to treat each one individually and offer them all wrap-around services.”

Residents can leave and return when they please and have guests, although the guests aren’t allowed to stay overnight.

In addition to the case manager, a “housing navigator” will work full-time to find the safe haven residents permanent housing.

A small group of homeless people who live near the site told the Oakland Tribune they didn’t want to live there because it seems too constraining. Damon “Pops” Scarbrough said he would have preferred if the city would just allow homeless people to set up their own encampment on the land.

“It’s a good idea, it’s just too controlling,” Scarbrough said.

Jared Jaxson, who is homeless and lives on Sixth Street, said many of the homeless in the area are addicted to drugs and would fear living in a monitored environment.

“People are trying to get their life together, but if you give them boundaries and rules, that’s like jail. Most of the people out here have been institutionalized. This is nothing but another institution,” he said.

DeVries said the city anticipates drug addicts moving in and does not expect people to stay sober.

“There will be some rules; people can’t just do whatever they want,” DeVries said. “On the other side of the coin, there will be safety and security, which they currently don’t have living on the street. It’s a choice they have to make.”

Operation Dignity, the nonprofit contracted by the city to provide outreach to homeless people, has been talking to people on nearby streets to inform them of the site. Operation Dignity workers reported to DeVries that more than 80 percent of those people were interested in moving in.

Nearby residents and business owners are also excited about the site, he said.

“By creating this and having it well monitored, we will also have a no-camping zone and will be getting rid of all the rats and garbage and things that have come with it,” DeVries said.

Oakland intends to clear the encampments near the site by the end of the year, DeVries said.

The site at Sixth and Brush is a pilot program, DeVries said. The city hopes to open more sites one at a time. The next one will be a city-owned lot near Martin Luther King Jr. Way and MacArthur Boulevard, Schaaf said. Oakland does not have a deadline set for that site.

“Every little thing we do is helping to mediate the immediate problem while we work on the long-term solution, which is permanent supportive housing,” Schaaf said.