One of them is his own son, Keith.

Keith Fairben, 24, responded to the call minutes after the first plane hit. He hasn't been heard from since the towers fell.

Ken and Diane Fairben have lost their only child, a young man with a penchant for saving lives. In May, he completed an 11-month EMT program at North Shore University Hospital in Manhasset. He had been working for four years as a medic at New York Presbyterian Hospital in upper Manhattan.

Also missing is his partner, Mario Santoro and another part-time worker from the hospital.

Today, the Fairbens and Presbyterian Hospital's chief operating officer, Dr. Herbert Pardes, will ring the 9:30 a.m. opening bell at NASDAQ as a symbol of the hard work and lost lives of the hospital's EMS workers. "These were the greatest guys," Pardes said. "They were committed to saving people."

"It was Keith's love and passion," said his father, who called him on his cell phone at 9:10, minutes after he heard about the plane crash. "I knew he would be there," he said. The 6-foot-3, 240 pound medic loved helping people, he added.

He wasn't surprised when his son answered the phone and said: "Dad, I'm really busy. I'm at the World Trade Center. I can't talk now."

Be safe, his father said. "Call us later."

By 5 o'clock that evening, Fairben called his son's dispatcher and asked how everything was going. "Keith and Mario are missing," he was told. "They found their ambulance. But they were not there."

Mario Santoro has a wife and 2-year-old daughter. Fairben and his partner had been riding together for four months. Keith, who lived with his parents in Floral Park, was also a volunteer firefighter.

Last Thursday, Ken Fairben and his fellow firefighters drove into the city to help in the efforts. They spent seven hours digging in the rubble. "I went in expecting to bring Keith home," Fairben said yesterday. "The toughest thing was turning around after seven hours and walking away."

The hospital also lost seven of the nine ambulances that responded to the scene, and two command vehicles. Jack Delaney, director of emergency services for New York Presbyterian, said that the hospital had dispatched about 30 medics that morning. Ironically, one of the two ambulances spared in the attack had been manned by the two missing emergency medical technicians. "We were all caught in the collapse of the buildings," Delaney said.

The entire unit - and the entire hospital - is in mourning.

On Tuesday, 1,200 volunteer firefighters, EMS workers, hospital workers, and family and friends of the lost medical technicians met for a memorial service in Manhattan. They walked from the heliport on 60th Street to the boat basin in Central Park.

"Keith's parents are incredible," said Delaney. The staff wanted to meet them last week, and Fairben told them that this is where his son wanted to be.

"I know that when they find him, he will be with someone. He wouldn't abandon anyone," Fairben said.

Two weeks ago, Keith arrived home to find his uncle in the throes of a ruptured aorta. He recognized the signs and immediately began life-saving treatment. Unfortunately, he didn't make it through. He was devastated, his father recalls. "It's God's hand," he told his son.

Now, he takes those words to heart. "We are realistic. I know that he wouldn't have wanted to be anywhere else."

Jamie Talan (Newsday Today)