NTSB spokesman Peter Knudson says the helicopter crashed after striking the trees. Authorities say the site of Tuesday night's crash site in Coolbaugh Township is about a mile from the airport.
The NTSB says it will be conducting an investigation on the crash throughout the week.
Authorities have identified the victims as 52-year-old William Ellsworth, of Califon N.J., and 51-year-old Tighe Sullivan, of Darien, Conn. A third man, Stephen Barral, of Bernardsville, N.J., was seriously hurt.
Officials say the men were on their way back from a golf outing in New York and hit bad weather.