Federal postal investigators are investigating why a car slammed into a neighborhood post office early Sunday morning in San Jose, California.

The post office building caught fire and was engulfed in flames after the car went into it.

The man arrested for the incident was Richard Tillman, who is the brother of late NFL star turned U.S. Army Ranger Pat Tillman, according to San Jose Police.

Richard Tillman, 44, was booked on suspicion of arson into the Santa Clara County Jail.

“Shortly after 3 a.m. the San Jose Fire and Police Departments responded to reports of a vehicle on fire in the box lobby area at the Almaden Valley Station Post Office. The fire was extinguished with no injuries,” the U.S. Postal Inspection Service said in a statement.

Federal investigators told ABC News they are aware of and investigating spray-painted words found on the post office building and claims that the driver live-streamed driving the car into the building.

The connection of the spray-painted words to the incident is not clear at this point, sources familiar with the investigation told ABC News.

It is unclear if the driver was impaired.

ABC News has reached out to the Pat Tillman Foundation for comment from the family.

Pat Tillman put his NFL career with the Arizona Cardinals on hold following the Sept. 11 attacks and enlisted in the Army. He was killed by friendly fire while serving in Afghanistan in 2004.

Anyone with information is encouraged to contact postal inspectors at 877-876-2455.