About 1,000 soldiers combed rugged terrain in sweltering heat Tuesday, searching for a soldier from Paso Robles, Calif., who was last seen walking into the desert after leaving a note on his bunk declaring he wouldn't be back.

Spc. John R. Fish, of the Fort Hood-based 41st Fires Brigade, was reported missing Monday after he failed to show up at a morning roll call at the camp, officials at Fort Bliss said.

Fish, a 19-year-old ammunition specialist, left a note on his bunk that read: "I have some things to take care of. I won't be coming back," said Col. Dick Francey, commander of the Fort Hood unit.

Francey said the next 48 hours were critical for Fish, who was believed to have 2 1/2 liters of water but was enduring temperatures in the high 90s in the rocky desert. He had two cell phones with him, but they weren't turned on, according to the phone company.

"I just want him back," Francey said. "I just want him safe and sound back here."

Earlier this year, Army Sgt. Lawrence Sprader went missing on a training exercise at Fort Hood and was found dead from exposure four days later. An Army report detailed missteps by base officials in that case.

Fish served in Iraq for a year, returning in November, but there was no indication that he was depressed or wounded, Francey said. No one has heard from him in Killeen, where he lives off the post, and his mother in California hasn't heard from him.

"This totally surprises me. I would never expect him to do something like this," said Pfc. Michael Justman, who described himself as Fish's best friend and said the young soldier didn't seem to be upset recently.

Fish was spotted Monday morning at this desert training range about 30 miles northwest of the main post at Fort Bliss, near El Paso, Texas. Francey said he believes Fish walked south into the desert wearing fatigues and boots, and carrying a weapon similar to an M-16. It wasn't clear whether he had ammunition, and Francey said no ammunition was missing.

The brigade is at the camp for field artillery training.

Francey said it wasn't unusual for Fish to take off for six- to eight-hour walks on weekends, but he usually did that off-duty.