A man is accused of brutally attacking a sleeping passenger on a United Airlines flight Monday afternoon, leaving blood and bruises, according to federal authorities.

The attack occurred on a flight from San Francisco International Airport in California to Dulles International Airport in Virginia, according to court documents.

Authorities said that about two hours into the flight, Everett Chad Nelson left his seat in 35F and went to the restroom at the front of the plane.

On the way back to his seat, Nelson allegedly stopped at seat 12F and “without notice, began physically attacking a sleeping male passenger, repeatedly punching him in the face and head until blood came out of him,” the statement said Court file.

The victim, who is not identified in court documents, woke up screaming.

During the alleged minute-long attack, blood was splattered on Nelson's coat, seat, wall and window, the filing said. The victim had bruises on his eyes and a cut on his nose. He was treated by a doctor on the flight.

Authorities said a fellow passenger intervened and monitored Nelson in a seat near the front of the plane until it landed in Virginia. There were no further incidents on the flight.

According to the files, Nelson had no visible injuries and it does not appear that the victim hit him in self-defense.

United Airlines thanked its customers and crew members for quickly restraining Nelson.

“The flight landed safely and was met by paramedics and local police,” the airline said in a statement.

Nelson was charged with assault by beating, punching and wounding. His attorney did not immediately respond to a request for comment Thursday.