Amid a hoarder-like interior, police found 22,000 rounds of ammunition, 12 guns and other weapons in the home of the gunman in the San Jose rail-yard massacre, offering insight into the killer even as questions about one of California’s deadliest mass shootings continued to pile up. How did a long-time disgruntled employee walk onto his work site and kill nine people Wednesday? At one point, security videos show, he strolled across the.