SACRAMENTO, Calif. - A 21-year-old Sacramento-area man became the second California firefighter to die battling wildfire this year, as a series of lightning strikes ignited blazes in the drought-parched Sierra Nevada over the weekend.Michael Hallenbeck, of the Sierra foothill community of Shingle Springs, was killed on Saturday as he and his firefighting crew tackled a blaze near Lake Tahoe in Northern California, the U.S. Forest Service said on Sunday.Dave Ruhl, 38, died last month fighting another Northern California fire."The grief we are feeling at the sudden loss of two of our firefighters, Dave Ruhl ... on the Modoc National Forest and now Mike Hallenbeck on the Basin, reminds us of the sacrifices these men and women make every day," US Forest Service Pacific Southwest Regional Forester Randy Moore said in a statement.On Sunday, family members buried Ruhl, a married father of two from South Dakota, who died of smoke inhalation and carbon monoxide poisoning battling the Frog Fire in the Modoc National Forest on July 31.Erin Ruhl, who survives him along with two children, said the 38-year-old was an active outdoorsman."He loved to hunt, ski, bike and hike," she said in a statement released by the Forest Service. "He made lasting friends from all over and had an awesome sense of humor."The fire that killed Hallenbeck was one of several dozen that broke out Saturday after lightning strikes in Northern California forests, the Forest Service said.Forest Service spokeswoman Lisa Herron said that Hallenbeck died after he was hit by a falling tree and that the agency was investigating the incident.