BEDFORD, Mass. -- Federal investigators Monday recovered critical flight recording devices from the wreckage of the private jet that crashed here upon takeoff, killing Lewis Katz and six other people.

The National Transportation Safety Board made the announcement at 6:21 p.m. on Twitter: "Cockpit voice recorder and flight data recorder just recovered from Gulfstream IV involved in Saturday's accident in Bedford, MA."

After federal investigators used a crane to lift the tail of the plane, workers waded into the watery gully where the Gulfstream IV had broken into pieces after bursting into flames and retrieved the recording devices, which they hope will explain the cause of the crash.

At 9:40 p.m. Saturday, the plane was headed to Atlantic City International Airport following a day during which Mr. Katz and three friends attended an education fundraising event at Concord at the home of historian Doris Kearns Goodwin and her husband, Richard Goodwin, an adviser to Presidents John F. Kennedy and Lyndon B. Johnson.

In 911 calls released Monday, neighbors described a loud explosion and towering column of smoke. One caller Saturday night said it looked like "an atomic bomb went off" and described "a mushroom cloud" of smoke and fire.

Among Mr. Katz's traveling companions was Anne B. Leeds, 74, a retired schoolteacher and a neighbor of Mr. Katz's in Longport, N.J. Mr. Katz had invited Ms. Leeds, a mother and grandmother, on the trip at the last minute as the two met on the beach Saturday.

Also on the plane was Marcella M. Dalsey, 59, executive director of the Drew A. Katz Foundation -- named after Mr. Katz's son -- and president of the KATZ Academy Charter School, which she cofounded with Lewis Katz in 2012. Ms. Dalsey was the mother of four grown children.

Susan K. Asbell, 68, of Cherry Hill, N.J., was Mr. Katz's third guest. A mother of two and wife of former Camden County Prosecutor Sam Asbell, Mrs. Asbell was a member of the planning committee of the Boys and Girls Club of Camden County, an organization close to Mr. Katz's heart.

The district attorney for Middlesex County released the names of two of the plane's crew: James McDowell, 51, of Georgetown, Del., the pilot, and Teresa Ann Benhoff, 48, of Easton, Md., a flight attendant.

The copilot was Bauke "Mike" de Vries, 45, of Marlton, N.J., his wife, Shelly, confirmed. She said that the crew had flown Mr. Katz for more than a decade.

First Published: June 3, 2014, 3:18 a.m.