A United Airlines flight from San Francisco International Airport to Washington Dulles International Airport terrified passengers Monday when one of the passengers attacked a deaf, nonverbal man who was sleeping on the plane.

Sandhya Gupta, a witness to the incident, said the attacker was wearing a neon green jacket and began attacking the man sitting in front of Gupta two hours into the nonstop flight.

According to an FBI affidavit, passenger Everett Nelson had just exited the restroom when he physically attacked a sleeping male passenger, repeatedly punching him in the face and head until he drew blood.

A United Airlines flight from San Francisco International Airport to Washington Dulles International Airport terrified passengers Monday when one of the passengers attacked a deaf, nonverbal man who was sleeping on the plane. Jodi Hernandez reports.

“I could see blood flowing when he was hit,” Gupta said. “My first thought was that I was just wondering if the attacker had an object because I didn't know you could do that kind of damage with your bare hands.”

Gupta added that she and another woman came to the victim's aid only when another passenger grabbed the attacker.

The victim, who is also deaf and speechless, suffered facial cuts, a black eye and bruises, according to Gupta.

The flight crews then brought the attacker to the front of the plane, and instead of restraining him, a crew member watched over him.

Gupta said the decision made many on board nervous.

“(The victim) felt unsafe because his attacker was a few rows in front of him and he continued to write and show us. I am scared and feel unsafe,” Gupta said.

Aviation expert Mike McCaron said the crew's handling of the incident was puzzling because standard protocol was to restrain the suspect – usually with plastic cuffs – and find a nearby airport where he could land.

Instead, the United flight flew the remaining three hours to Dulles.

“The normal thing is that you want to be on the ground as quickly as possible, firstly, to provide first aid to the person who is attacked and secondly, to get the person off the aircraft and into the custody of law enforcement,” McCarron said.

In a statement, United said: “Thanks to the quick actions of our crew and customers, a passenger was restrained after he became physically aggressive towards another customer. The flight landed safely and was met by paramedics and local law enforcement.”

Gupta said the crew appeared prepared to handle the situation or assist a traumatized and injured passenger with a hearing impairment.

“It shouldn’t happen; it just shouldn’t happen to anyone,” she said.