A preliminary report by the National Transportation Safety Board revealed few new details surrounding the cause of a fatal plane crash in Crystal Lake in recent weeks. 

Hugh Scott Clark, 65, of Lake Forest, and Paul San Filippo, 82, of Grayslake, died in the crash, according to the Northwest Herald.

The report released by the NTSB confirmed San Filippo was piloting the Beech S35 Bonanza, which he owned, at the time of the crash at 3:15 p.m. May 3. The plane went down in a marshy gravel pit on the east side of Pyott Road, across the street from the airport. 

The plane took off from the Lake in the Hills Airport, according to the report. Witnesses reported the plan flying low to the ground "in a very steep bank." A witness said the airplane continued to descend at a steep angle before hitting the quarry, according to the NTSB report. 

"For reasons unknown at this time, witness statements indicate the plane may have been attempting to return to the airport when it began to decelerate just prior to impact," according to a Crystal Lake Police Department press release provided to media outlets after the crash.  

Weather conditions were clear at the time of the flight with visibility for 10 miles and few clouds in the sky, according to the NTSB report. 

The preliminary NTSB report is attached as a PDF file in this article.