James O'Rourke, and Terence Corcoran

PATTERSON – Authorities are searching for an Albany-area teen in need of medical care who hasn't been seen since walking away from the Green Chimneys campus early Sunday evening.

Nick Alber, 17, stands about 6-feet-3-inches tall and weighs about 170 pounds. He has short brown hair, brown eyes and was wearing red or blue basketball shorts and a black and white T-shirt emblazoned with the word "Brooklyn" when he disappeared about 6 p.m.

Frederick Alber, the teen's father, of Niskayuna, New York, said he had no idea why his son would choose to venture out on his own.

"We spoke with him the day before he left and he seemed OK. It was the first week of school and he was doing fine down there," Frederick Alber said Wednesday.

The teen likely did not have direct access to a car, but may have been able to hitch a ride with a stranger or two, Frederick Alber said.

"He's had one or two instances where he's gone to Danbury and New Milford," he said. "We have reason to believe he could be anywhere downstate. There's no rhyme or reason to where he might go."

The father said he believes his son may be moving south of the Putnam area to avoid being found.

The Alber family has been frantically searching for the 17-year-old since he left Green Chimneys, a nonprofit facility for children with emotional and behavioral issues, and has scoured shopping malls and street corners across the Lower Hudson Valley and Connecticut.

Word also has spread through social media; a Facebook post with information on Nick Alber and his disappearance had, by Wednesday evening, been shared more than 6,570 times.

Frederick Alber urged anyone who may have seen his boy to contact their local police department, the Putnam County Sheriff's Office at 845-225-4300 or the National Center for Missing and Exploited Children, 1-800-843-5678.

Authorities and staff at Green Chimneys were unable to comment on the case Wednesday night.

@JORourkeT800