PHILADELPHIA (AP) — Plans to open what could be the nation's first medically supervised injection site in Philadelphia were put on hold Thursday night amid strenuous opposition from a federal prosecutor and residents of the neighborhood where it would have been located.

Mayor Jim Kenney said that Safehouse agreed to push back its opening date so it can meet with members of the community and hear their concerns. Meanwhile, the owner of the medical complex in south Philadelphia where Safehouse planned to operate its first injection site abruptly pulled out, leaving the project in limbo.

“After Safehouse voluntarily delayed its opening so it could focus on meeting with the community, the building owner alerted the city that he was no longer interested in moving forward with the lease,” Kenney said in a written statement.

“In light of this development and the strong concerns voiced over the past two days, it’s clear that no site will open imminently," he said.

The fast-moving developments came after U.S. Attorney William McSwain indicated his office would appeal a judge's ruling this week that had paved the way for Safehouse to open. McSwain also asked U.S. District Judge Gerald McHugh to stay his decision while the appeal unfolds.

Safehouse organizers believe the injection site could save lives as the city grapples with about 1,100 overdose deaths each year. However, McSwain and many neighbors fear the program would only encourage illegal drug use.

“The sad fact is that Safehouse’s secretive, haphazard ‘plan’ has not been vetted with any of the affected neighborhood residents, community groups, city council members, state representatives or state senators. It is being unfairly foisted on them on the assumption that they don’t matter,” McSwain, a Republican appointed by President Donald Trump, said in a statement earlier Thursday.

Under the Safehouse plan, people could bring drugs to the clinic-like setting, use them in a partitioned bay and get medical help if they overdose. They would also have access to counseling, treatment and other health services.

Safehouse organizers have said that about one person dies of an overdose each week in south Philadelphia. The nonprofit hopes to eventually place injection clinics in other neighborhoods, including Kensington, the epicenter of the city's opioid crisis.

But this week's announcement that Safehouse planned to open its first site next week and offer services four hours a day led residents to shout down former Democratic Gov. Ed Rendell and other organizers at a news conference.

Kenney, a supporter of the concept, said Thursday the delay “will allow Safehouse more time to examine its options, and to engage the community. It will allow those with concerns more time to get answers. And it will allow everyone to take a deep breath and focus on the ultimate goal of this effort: to save the lives of fellow Philadelphians who are struggling with addiction.”

The opening has been on hold for much of the past year while Judge McHugh held evidentiary hearings to determine whether the plan violates a 1980s-era drug law known as the “crackhouse statute.” McSwain believes it does and sued the Safehouse organizers. Along with Rendell, organizers include Ronda Goldfein, executive director of the AIDS Law Project of Pennsylvania.

McHugh found Safehouse did not run afoul of the law.

“The ultimate goal of Safehouse’s proposed operation is to reduce drug use, not facilitate it, and accordingly, (the law) does not prohibit Safehouse’s proposed conduct,” McHugh wrote in a preliminary ruling last fall that he affirmed Tuesday.

The facilities have long operated in Canada and Europe and have been considered by several U.S. cities, including Seattle, New York and San Francisco. Smaller, unofficial sites have also popped up in some places across the U.S.