A busload of people did nothing to stop a pack of teen girls from beating a pregnant teenager and her boyfriend despite pleas from the victims that she was carrying a baby.
The behavior was caught on the bus' surveillance camera and later helped police in Seattle locate the five attackers.
"I'm shocked," said Sgt. John Urquhart of the King County Sheriff's Department. "The video is shocking to look at.
"The ferocity, the intensity, the unprovoked nature" is shocking, he said. "But what shocks me most is that these girls thought they could do this on a crowded bus with adults and do it with impunity."
Urquhart said that the incident, which took place on Nov. 19, occurred just after 7 p.m., at the height of Seattle's rush hour. Five teen girls -- ranging in age from 14 to 19 -- boarded the bus and immediately spotted the victim, Jessica, whose last name ABC News is not using to protect her privacy, and the girl's boyfriend.
One of the attackers ripped headphones out of the young couple's ears and the altercation began.
According to Urquhart, one of the suspects said that the boyfriend had stolen her cell phone.
"The female victim has never seen any of these five girls before and the male victim said he'd been at a party where one of the suspects had been," said Urquhart. "But he denies ever taking her cell phone."
On the video, a girl is seen using her leg to thrust kick after kick into the boyfriend's head and torso. Another girl quickly approaches, taking swing after swing at the pregnant teen. Then three others join in, the pregnant teen getting crushed into a handrail.
Jessica was three-months pregnant at the time of the attack.
"Basically, I was turned around [and] one of the girls hit me from the back," Jessica told KOMO-TV, ABC News' affiliate in Seattle. "I turned around to ask, 'Hey, what are you doing?' and then three of the other ones started hitting me."
Jessica said she screamed twice about being pregnant and overheard one of her attackers saying, "Nobody hit her in the stomach."
"My main concern was for the baby," Jessica told KOMO. "None of them hit me in the stomach, but one of them was kicking me in the back and I just didn't want anything to happen."
Efforts made by ABCNews.com to contact Jessica were unsuccessful.
As for the lack of response by her fellow passengers, Jessica said she was shocked nobody helped her or her boyfriend.
"Out of all those people, I think somebody could have said something sooner," she said.
Jessica was treated at a nearby hospital for a wound over her eye and her unborn baby was said to be fine. Her boyfriend was uninjured.
Urquhart said that the bus driver immediately pulled over when he realized what was going on at the back of the bus, but the length of the vehicle and the large number of passengers in between him and the attack made it difficult for him to see what was happening.
"It takes a little while to register what is going on. That's human nature," said Urquhart. "We know that people don't jump in or help, or call 911 right away."
Urquhart said that the incident gives law enforcement an opportunity to reinforce how important it is for bystanders of a crime to speak up and call for help.
"This incident should cause our community to stop and reassess the level of juvenile violence we are willing to tolerate," King County Sheriff Sue Rehr said in a prepared statement. "Clearly, we should have no tolerance for this kind of vicious and unprovoked attack."