WHYY, the public-broadcasting television and radio affiliate in Philadelphia, disclosed to stunned staffers Thursday that Chris Satullo, the head of news and civic engagement, would leave the organization and that his last day at its offices on Independence Mall would be Friday.

WHYY CEO Bill Marrazzo did not detail a transition plan in a memo circulated to employees. An interim replacement for Satullo will be appointed while WHYY searches for a permanent one, he said.

Marrazzo called Satullo's departure a "change in the executive leadership team." Satullo's last official day at WHYY will be Sept. 11, according to the memo, but he will be "off site" after the close of business on Friday.

Thursday afternoon, Satullo met with dozens of newsroom staffers, some crying, outside in the heat at Franklin Square Park at Seventh and Race Streets, near the WHYY offices, and gave an impromptu goodbye speech.

Standing with his wife, Eileen Kenna Satullo, and dressed in khaki pants and a tan checked shirt without a tie, Satullo said that he realized the news of his departure came as a shock and that he regretted the timing because of the pope's upcoming visit and some other projects.

"I hope you'd agree that I've tried to be as transparent as possible with you guys," he told the staff members who gathered in Franklin Square, according to one who was there. "So please trust me when I tell you that I simply can't answer any of the questions that you might have right now."

Afterward, former colleagues came up to hug Satullo, wish him well, and say they would miss him.

Later in the day, a WHYY staffer said, "We are all shocked and saddened. Chris took WHYY's modest local news operation and grew it into a significant player in the city's media community."

WHYY declined to comment. "Because we respect the privacy of our employees, we don't discuss why anybody leaves the organization," WHYY spokesman Arthur Ellis said.

Satullo's departure was not discussed by the WHYY board, which was informed Thursday that he was leaving, and the newsroom budget was not threatened with cuts, said one board member who asked not to be identified.

Satullo, a longtime editor at The Inquirer who for years headed the newspaper's Editorial Board, joined WHYY in 2009. Though he was a vice president at WHYY, he worked directly with reporters on stories and projects, staffers said.

Under Satullo's leadership, WHYY started the Newsworks.org website, featuring news on the Philadelphia region, and he helped launch multi-station collaborations that explored issues arising from development of the Marcellus Shale region and urban issues in Pennsylvania.

WHYY includes TV and radio stations and a news staff that covers Southeastern Pennsylvania, South Jersey, and Delaware. Its more popular radio shows include the nationally broadcast Fresh Air with Terry Gross, Radio Times with Marty Moss-Coane, and NewsWorks Tonight.

WHYY employees declined to speak on the record about Satullo's departure. One called Thursday a "terribly sad day."

Satullo and soon-to-be-former colleagues gathered Thursday night for drinks at the Gaslight, a bar on Market Street in Old City. Satullo declined to comment, as did other Newsworks staffers.