RENTON, Wash. -- A 73-year-old man was stabbed and critically injured when he got involved in a fight between a group of teenagers and his grandson, according to police.

Police spokesman Dave Liebman said the alleged theft of a cell phone triggered the fight between teens at the Renton Transit Center on Thursday evening.

Amber Brown witnessed the incident said it looked as if one teen was being bullied by the rest of the group.

"I thought they were playing, but then they started taunting the guy, saying all this stuff," she said. "He was walking away basically, then they surrounded him and everything just broke off."

At some point during the incident, the group stole the teen's cell phone, according to police. The teen then went to call home and told his father and grandfather what had happened.

The two men arrived at the transit center several minutes later to try to get the phone back. When the men confronted the thieves, the group turned violent.

The teen whose phone was stolen was punched and kicked, and his grandfather was stabbed twice in the torso, police said.

The grandfather, identified by family members as George Rodgers Sr., was rushed to Harborview Medical Center in Seattle and remains in critical condition.

The victim's daughter, Linda, said Rodgers jumped in front of his grandson when he saw the knife.

"They started to stab him multiple times," she said. "It's blowing my mind that somebody would stab somebody three times over a cell phone."

Lind said Rodgers refused to budge even after he was stabbed, and didn't collapse until officers arrived.

"Whatever strength he had he used to wait for somebody to come to make sure his son and his grandson were protected," she said.

Police said an 18-year-old teen with stab wounds was found after the attack at Valley Medical Center. Investigators believe the teen was involved in the attack against Rodgers and his family, though the extent of his involvement is still under investigation.

The group of teens ran off when officers arrived at the Transit Center. Police have arrested three suspects, and said they're still looking for one more.

The incident happened during the evening rush, startling many bus riders and commuters who were horrified by the violent scene.

"It was pretty scary. I was shocked that the whole thing took place," said Brown.

The victim's family, meanwhile, is praying that his strength will carry him through the injuries.

Rodgers underwent hours of surgery and, while he remains on a ventilator, Linda said he is responding to her voice and moving his toes and fingers.

"(I) Hope he comes out of this so he can stand in front of those individuals and say 'you didn't kill me. I am still here,'" his daughter said.