The instant the severed hand fell to the ground, Milpitas roof-cutter Nathaniel Forrest knew exactly what to do.

He had plotted every move in countless mental rehearsals.The only thing he didn't expect was that it would be his hand.

Yet as the blood spurted from his left arm, Forrest took control, directing his stunned co-workers to apply a tourniquet and to retrieve his hand from the floor.

"Don't get excited," he told fellow roof-cutter John Shewchuck, "but I just cut my hand off."

Forrest's reasoned reaction to the Nov. 23 accident probably saved his life - and his hand. Two hours after the hand was cut off, doctors at San Jose Medical Center were already at work reattaching it. Eight hours later, doctors Seung Kim and Vincent Lepore had reconnected the severed bones, tendons, nerves, arteries and veins.

By Friday afternoon, hours after Forrest's third operation, doctors were optimistic.

"He's really a courageous man," Kim said. Now, after procedures to restore blood flow to his thumb and to remove dead muscle, Forrest's fingers are a healthy "pink and warm."

Forrest, who has two daughters, has worked around saws for more than a decade and with his hands for most of his 37 years.

Until last week, he had never had an accident. But he had repeatedly prepared himself for the day someone would lose a limb.

"I had always wondered if I was capable of looking at someone whose hand was just cut off and looking past that to what needed to be done," Forrest said from his hospital bed.

It was late afternoon, the evening before Thanksgiving, when the accident happened at the firm of Truss Comm in Milpitas, where Forrest cuts roofs for prefabricated houses and tract homes. The saw suddenly went out of control, and Forrest jerked back out of its way. He thought it had missed him, but then he felt the blood shooting.

"I looked at my arm and my hand wasn't there," he said.

The pain throbbed. He said he felt like his hand was still there, even though he knew it wasn't. It felt like someone had taken his hand and was crushing it.

As co-worker Shewchuck put Forrest's belt around his arm to stop the bleeding, his supervisor, Leopoldo Felix, called the fire department. Forrest lay down on a stack of lumber, fighting to stay conscious.

Then, he remembered his hand.

"I saw Harvey (Iese) and I said, `Harvey, you're not scared of my hand are you? Do me a favor, then, go find my hand and keep it cool. They might be able to sew it back on.' "

Iese found the hand and put it in the lunch room refrigerator until the paramedics arrived.

Ideally, Kim said, a severed limb should be placed in a plastic bag and then in ice water to slow deterioration of the cells. If a limb is placed on ice or dry ice, the tissue will freeze and die. Without a plastic covering, it will become waterlogged if exposed directly to water.

"It was not done exactly the way it should be done," Kim said, "but he certainly made the attempt and he was the only one to think of it."

Forrest has 16 weeks of bed rest ahead of him and physical therapy to restore the use of his hand. Although the reattachment appears successful, he is as realistic as he is optimistic. There is the possibility that he still might lose his hand if infection sets in.

"All I know is that as long as I'm alive, I'm OK."