OAKLAND (KPIX 5) — A man BART police hailed as a hero after he disarmed a stabbing suspect who attacked two people on a train at the Coliseum station in Oakland spoke exclusively to KPIX 5 Sunday evening about the frightening ordeal.

David Harris, a landscaper from of Oakland, suffered injuries himself when he stepped off the BART train and into action Saturday night to defend the couple and help apprehend the assailant.

BART Police on Sunday identified the suspect in the stabbing is 32-year old Robert Dolph of San Francisco. Dolph seemingly attacked his victims at random.

“The attack appears to be entirely unprovoked and there’s an unknown motive,” said BART Deputy Police Chief Lance Haight.

Investigators said the two victims — a man in his 50s and his sister, a woman in her 60s — got on a BART train at the South San Francisco station.

“While they were on the train, they noticed this man get on the train who was pacing back and forth muttering to himself and shouting things out,” explained Haight. “They became alarmed by his behavior, so when the train arrived at the Coliseum BART station, they tried to elude him as fast as they could.”

As the siblings disembarked, police said Dolph attacked them with a large, fixed blade knife.

Both victims were stabbed in the head, while the male victim was also stabbed in the chest, according to police.

The male victim remained in critical condition Sunday, said Haight. His sister had less serious injuries and her condition was described as fair.

“The woman had collapsed to her knees and her brother, I guess it was her brother, was fighting him,” explained Harris.

Harris said he saw the couple getting attacked when he intervened. He jumped on Dolph and grabbed his arm to take his knife away, getting his fingers on both hands sliced in the process.

“He was really strong. It took four of us to turn him over on his stomach,” said Harris.

Cell phone video shot of the scene shows several bystanders helping to hold Dolph down until police could arrive.

BART police thanked all of the Good Samaritans who stepped in to help the victims, but singled out Harris for praise.

“This man that intervened is a hero, very courageous,” said Haight.

Police say the suspect confessed, but did not give a coherent answer as to why he attacked the man and woman.

Harris said that during the dangerous encounter as he wrestled the knife from Dolph’s grasp, the stabber was “talking gibberish.”

There were no reports of anyone having an argument or even a conversation with Dolph.

Police said the suspect kept babbling incoherently and for some reason got fixated with these two people, followed them off the train and attacked them.

Dolph was arrested booked into Santa Rita Jail in Dublin on two counts of attempted murder.