PHILADELPHIA (CBS) — When someone saves your life, what can you say to him?

Joseph Lozito waited to return a phone call from his Good Samaritan, because it was so emotional. He knew his voice immediately, but was now grateful to know his name. After hello, the first words Alfred Douglas heard were, “I owe you my life.”

The two men — one from Philadelphia, the other from Queens met on New York’s “3 train” — a subway route they were forced to take when the “E train” was out of commission. Little did they know, the ride would put them both in harm’s way.

Saturday morning, NYPD was working every lead. Within 28 hours, a serial killer had taken four lives and wounded four other people. The picture of a suspect was released, but neither Lozito — on his way to work at Lincoln Center — nor Douglas — on his way home to Queens would recognize a disturbing looking man in their subway car.

“All the time were on the train, my eyes were on him,” Douglas says.”He got up, he was pacing back and forth.”

Lozito thought the man looked dirty. He saw that a woman moved her seat, when this man sat next to her.

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After what sounded like an altercation with two officers near the motorman’s cab, Lozito describes what happens next.

“He stops a few feet from the door, a few feet from me and stares at me. We’re face to face, we make eye contact, he pulls out a knife and says, ‘You’re gonna die.’ Then, he lunged at me.”

An eight inch blade was flashed. Time seemed to move in slow motion for Lozito, until he says his adrenaline kicked in, with anger. Lozito tackled him, and held him down, while police tried to handcuff the perpetrator. In the scuffle, Lozito’s head was slashed over and over again. Blood was gushing. Now Lozito needed help. He was afraid. That’s when he heard a voice.

“I was telling him, ‘Joseph, you gotta keep calm.'”

It was the voice of Alfred Douglas, a carpenter at Ground Zero. Lozito’s Good Samaritan.

“He was trying to calm me down,” says Lozito, “and he just applied direct pressure to my neck.”

Douglas says he first put pressure on the wounds with his bare hand and then yelled if anyone had a napkin or towel. He concentrated on the worse wound, which was on the back of his neck. Douglas worried with medical help taking so long to arrive, that Lozito could bleed to death.

Lozito could feel Douglas working, but he never saw his face and didn’t know his name. But he remembered his voice.

On Wednesday night, Douglas found the Lozito family phone number in Philadelphia and called to re-introduce himself.

“As soon as I heard his voice on the phone, I got chills,” says Lozito. “I got goose bumps because this is the guy who helped me.”

A humble guy.

“You can’t just live your life for you alone,’ says Douglas, “you have to live your life to help others.”

On the phone, there were a few tears and a few laughs. Douglas teased Lozito who stands at six-foot-two, for being such a big guy and crying in the midst of the crisis, when he thought he was going to die.

He was crying for his family, Douglas remembers. “He said, ‘I got two boys. I love my kids, I love my wife.'”

Now, it’s tears of gratitude.

“I thanked him profusely and told him, I owe my life to him,” said Lozito.

Near his job site, at Ground Zero, Douglas — in a hard hat and reflective vest — had a final word.

“Joseph, I’m happy you’re still around. Stay strong, get better and take care of your family.”

Both men believe that a power greater than themselves brought them together on Saturday. It reminds Douglas of something his Jamaican grandmother taught him.

Be helpful. Any time that you can render assistance, do it. This world is not about you, there are others to help.

Tonight, Joe Lozito is teaching his own young son, that very lesson.

Reported by Pat Ciarrocchi, CBS 3