Investigation underway after small plane crash in Danbury

The Federal Aviation Administration was at the site of Sunday's plane crash in Danbury as officials continued to try to piece together why the single-engine plane went down, sending three men to the hospital.
The National Transportation Safety Board has officially taken over the investigation, News 12 is told.
The incident happened just outside of Danbury Airport near a dog park on Miry Brook Road before 10:30 a.m. Sunday. 
All three men remain in the hospital, one in critical condition, one in serious condition and the other with minor injuries.
Airport officials said a crane and flatbed truck would arrive at the scene Monday evening to remove the plane from the hill. The removal had to be be coordinated with an insurance company, the National Safety Transportation Board and the Federal Aviation Administration.
Officials say the three men on board had rented the plane from a fixed-base operator earlier that morning. Their destination wasn't known.
The NTSB has not yet released the identities of the three men involved. 
A spokesperson says a preliminary report on the crash is expected by the end of the week.