Gov. Arnold Schwarzenegger praised Allen's service, saying he served his country proudly and bravely.
According to Allen's MySpace page, he graduated from Santa Ynez Valley Union High School in 2002. He posted photos from Iraq and stories from the frontlines on the site.
As of Tuesday, at least 4,200 members of the U.S. military have died in the Iraq war since it began in March 2003, according to an Associated Press count.