Clarification: An earlier version of this story incorrectly stated Matthew Palmer's age.

A full investigation into the Addison plane crash that killed 10 people Sunday could take up to 18 months to complete, the National Transportation Safety Board said Monday in a press conference. The plane's cockpit voice recorder has been recovered and is in the process of being downloaded for analysis, the NTSB said.

The 2017 twin-engine Beechcraft BE-350 King Air did not have a flight data recorder, which would have recorded the telemetry, or internal flight data, of the plane. 

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However, NTSB officials said Monday there were "multiple videos of the crash" from around the airport that they will be able to use in their investigation.

RELATED: Family of 4 among 10 killed in Addison plane crash

The N-number on the tail of the plane that crashed was N534FF, and was in the process of being changed to N511EF, NTSB officials said Monday. The flight was headed to St. Petersburg, Fla. 

The plane crashed into a hangar shortly after taking off, officials said Monday. The plane veered to the left, rolled over and clipped the hangar. 

NTSB officials said they have no official cause for the crash yet, but are reviewing pilot records and maintenance records, and conducting interviews to determine what happened.

The communication between pilots and the air traffic control tower were normal, the NTSB said Monday. The aircraft was cleared for takeoff. There were no further communications between the pilots and tower before the crash.

Investigators are considering weight and engine failure as possible causes, but nothing is known for certain yet. 

Eight passengers and two crew members were on board the plane, including siblings Alice and Dylan Maritato; their mother, Ornella Ellard; and stepfather, Brian Ellard. Alice was a student at John Paul II High School, and Dylan attended All Saints Catholic School.

Additionally, two more victims were identified on Monday by the Dallas County Office of the Medical Examiner. Stephen Lee Thelen, 58, and Matthew Palmer, 28, also died in the crash, according to a release tweeted by Judge Clay Jenkins.

There were no survivors of the crash, and the plane was destroyed by fire. Officials have confirmed that there was no one else in the hangar at the time of the crash. 

This crash was deadliest Texas plane crash since Sept. 12, 1991, when 14 people died in Eagle Lake on a plane headed to Houston.

This is a developing story. Check back for new information. Download our free WFAA app to stay up-to-date on all news stories in the Dallas-Fort Worth area.