KATTERBACH, Germany — Spc. Joshua Whitmer stood in his kitchen, putting away groceries, when he smelled the smoke.

No big deal, he thought — probably somebody barbecuing outside. The sun was shining that Saturday afternoon, and many of his neighbors at Katterbach Casern had just returned, as he had, from a year in Iraq.

Then Whitmer looked out a back window and saw his golden retriever, Bowser, running and jumping crazily. Smoke poured from beneath his balcony, from a basement storage locker one floor below.

Whitmer sprung into action. In the next half-hour, he would alert several of his neighbors to the fire and enter the burning storage locker repeatedly to put out the fire. His efforts earned him a night in the hospital for breathing too much smoke — and the gratitude of many of his neighbors.

“Nobody else came back in the building but him,” said April Miller, Whitmer’s next-door neighbor. “He’s our hero.”

Few others in Building 5948HH had even met Whitmer before the April 23 fire. The quiet 20-year-old, an AH-64 Apache crew chief from the 1st Infantry Division’s 1st Battalion, 1st Aviation Regiment, already has served two tours in Iraq.

But they saw and heard him that day. Whitmer pounded on Miller’s door until he got the attention of Jessica Miller, 16, who was home with two friends watching her two younger brothers.

Then he dashed up one flight of stairs to the apartment of Spc. Sharisha Harvey, 31, who was napping. Her daughter was in the next room and answered Whitmer’s knocking at the door.

“My daughter said, ‘Mom, get up! The house is on fire,’” Harvey recalled.

Racing back down to his apartment, Whitmer yelled at his wife, Elizabeth, 21, to get out with their two children, Edmund, 5, and Jeffrey, 9 months. Then he ran to the basement, where he found the fire in Harvey’s storage closet.

“The first thing on my mind was, it looked intentional,” Whitmer said. “It looked like a pile of garbage. It didn’t look like a way anyone would store anything.”

He grabbed a large fire extinguisher and blanketed the fire with foam. Unsure whether the blaze was out, he braved the smoke to return at least six times, emptying two extinguishers.

Finally, with the help of a neighbor, he broke a window and ran a garden hose into the room. That did the trick. Only then did firefighters arrive, to mop up the fire and to treat Whitmer and two others suffering from thick smoke. They gave him oxygen and sent him to the hospital overnight.

The building’s residents later complained the fire department took 20 to 30 minutes to arrive after the fire started. Stefan Grötschel, the base fire chief, said the station received the first of several calls at 4:34 p.m, and two firetrucks arrived at the 12-unit apartment by 4:39 p.m.

He said residents may have forgotten to call in their haste and confusion. He also complimented Whitmer on his quick thinking but cautioned that it is best for residents to leave a burning building instead of trying to fight the fire.

Jim Hughes, a spokesman for the 235th Base Support Battalion, said investigators have ruled out faulty wiring and arson as causes of the blaze. They believe youngsters playing or smoking in the basement may have set it.

About $2,000 damage occurred to Harvey’s locker. She said the biggest losses were Christmas decorations and spare Army gear. “I’m just glad nobody was hurt,” she said.

Hughes said Whitmer has been nominated for the BSB’s “Superior Citizen Award.” The residents of 5948HH bought him a big thank-you card and a gift certificate, much to his embarrassment.

“I’ve already received more than I should,” he said.

His neighbors don’t agree.

“Not many people,” Harvey said, “would put their lives on the line like that.”