"This is one of the last places we want to look at. None of us are comfortable with having to take these drastic steps," the mayor told NY1 on Tuesday. "Each gym, the 20 gyms that we are looking at, we have not made a final determination on all the gyms, but that we are looking at are separate from the actual school buildings. They are independent from the school buildings."
The mayor did not reveal all of the locations but the first six appear to be in Brooklyn.
In a letter sent to parents of students who attend the affected schools, obtained by ABC New York station WABC, school officials promised migrant "individuals and families" would be confined to the school's standalone gym saying: "This should not impact school operations, nor will the families have access to any other part of the school where students and staff are."
The news angered some parents and community members who showed up at some schools protesting the mayor.
"We're not against them. They are all welcome, just not to our school, [and] next to our children," Armis Rosa, a parent of a student at a Brooklyn school that will be used to house migrants, told WABC.
At least 65,000 asylum-seekers have come through the city so far, including 4,200 last week alone, officials said. Adams said the city expects as many as 15 buses this weekend.
"I'm really calling on all of us to take notice that this is going to impact every city service that we deliver to the people of this city. And it's just wrong. New York City should not be carrying a burden of a national problem." Adams told Fox 5 in an interview on Tuesday. "Our goal is to manage a crisis that we're facing in partnership with the entire state."
The reception in the city's northern suburbs has been mixed. In Westchester, three buses of about 40 adults with young children arrived at the Ramada in Yonkers last night. In Orange County, two hotels in Newburgh accepted some migrants, however, a judge issued a temporary restraining order against the city Tuesday that prevents the mayor's office from sending more migrants.
Orange County officials said that the city was planning on sending seven busses of migrants to the county Tuesday.
"New York City should not be establishing a homeless shelter outside of its borders in Orange County," Orange County Executive Steven M. Neuhaus said in a statement.
A spokesperson for Adams told ABC News in a statement that the administration is reviewing all of its legal options.
"We need the federal government to step up, but until they do, we need other elected officials around the state and country to do their part. New York City is out of space and we're only asking Orange County to manage approximately one-fourth of 1% of the asylum seekers who have come to New York City, with New York paying for shelter, food, and services," the spokesperson said in a statement.
The 186 migrants who are residing at a hotel in Orange County will be allowed to stay in their rooms, however, if any of those individuals leave the hotels, New York cannot send other individuals to replace them, according to the TRO.
The next court hearing in the case is scheduled for June 21.
Officials representing some New York other suburbs also rebuked Adams' plan to send migrants to their towns for shelter.
Rockland County's top official declared a state of emergency on Saturday in response to Adams' plan to send 340 adult male migrants to live at an Armoni Inn and Suites in Orangeburg, New York, for four months.
Following the lifting of Title 42 -- a pandemic-era rule that allowed the easier expulsion of migrants -- Texas Gov. Greg Abbott has continued to bus migrants to major cities like New York. Local, state and city officials have voiced concerns about a lack of planning to accommodate the migrants as New York operates a shelter system above capacity and vows to send migrants to counties that have already declared a state of emergency.
New York Gov. Kathy Hochul sent a letter to President Joe Biden last Friday requesting assistance from federal agencies to house migrants on federal land in New York, including military facilities.
As of Friday last week, New York City is beyond capacity for its shelter system with over 36,700 migrants housed across 120 locations, according to Hochul. She added that with no more shelter space, 40% of "mid-level hotel stock" in New York City is used for short-term respite centers.
ABC News' Quinn Owen, Peter Charalambous, Teddy Grant, Jaclyn Lee, and Christopher Donato contributed to this report.