Stefan Pakulski, Hallowell city manager since September and formerly town manager in Readfield, died unexpectedly Saturday night.

An email sent Sunday from Hallowell Mayor Mark Walker said he was told that Pakulski, who lived in Wayne, died after suffering a heart problem. However, a woman speaking on behalf of the family Sunday said they had yet to learn what caused the death.

Pakulski, 57, had worked for 12 years as Readfield’s town manager until resigning in February 2015 and then signed a three-year contract as Hallowell’s town manager in September 2015.

Prior to his job as town manager in Readfield, Pakulski worked as community initiative program director for the Rockland-based Island Institute, a nonprofit organization that works on behalf of Maine’s island communities. He previously worked in international economic development.

He was married to Lynette Johnson, with whom he had two children, one in college and the other in high school.

“Our first thoughts are sorrow and condolence for the family,” Walker said Sunday in a telephone call. “It’s a big loss also for the city. He had stepped in, and in five or six months, he had made a big difference.”

Walker said Pakulski had a medical incident recently when he left the office to go to the hospital, but later told other Hallowell officials it was not heart-related.

Walker also said Pakulski had just concluded a vacation skiing with his daughter, who skis with Maranacook High School ski team. He also had flown to Utah to be with his son, Kai, and skied there, returning just a week ago.

“He is a huge loss,” said longtime friend Stephen Hayes of Readfield, who served with Pakulski on the board of directors of Regional School Unit 38, the Maranacook Area Schools. “His familiarity with town government made it a lot easier for us to work with the selectmen. He was inventive, creative and very well respected. Whatever he recommended, he generally convinced the board because of his excellent capabilities.”

Hayes also said the two had been soccer coaches together.

“He was a great soccer coach and a lot of fun. He had a terrific family and appeared to be in the best of health. It really comes as a shock,” he said.

Pakulski joined the school board recently. His wife, Lynette Johnson, previously had served on it for a number of years.

The family is expected to speak Monday about funeral arrangements, according to the family friend.