McCarthy said he stressed to federal officials his group's mission of providing a range of services — education, health care, mental health — and not just temporary shelter.
He pointed out that many of the children are fleeing violence in Central America and undertook a harrowing journey to cross the border.
"It's a traumatic event, one that would cause you to leave your country," McCarthy said. "Our concern would be to make sure that the plan, in addition to safety and shelter, was also designed to meet all the needs of the children."
The decision to pull the plug on Metro West appeared to have been made recently. A Health and Human Services document dated Wednesday and obtained by The Baltimore Sun notes the administration was still "waiting for official, signed agreements" between the HSS and the Federal Emergency Management Agency for the "sheltering of unaccompanied children at the Baltimore facility."
An HHS spokesman said by email he could not disclose the location of nonmilitary shelters being set up to house the children. Pressed on the point that Metro West was no longer being considered as a shelter site, the spokesman did not respond and then did not return follow up phone calls.
Gov. Martin O'Malley, speaking on the issue Wednesday for the first time, took no position on whether the downtown complex was an appropriate place for a shelter.
"That's a decision a local government would have to make," he said. "We as a state are willing to help any jurisdiction in the state that is willing to find a way to alleviate this humanitarian situation."
Baltimore Sun reporter Michael Dresser contributed to this article.