The domestic-violence arrest of San Francisco 49ers linebacker Reuben Foster stemmed from his girlfriend’s accusation that he physically dragged her during an argument at a Los Gatos home Sunday morning, according to sources familiar with the investigation. The reported victim, who has been in a relationship with Foster for several years, also told police dispatchers during a 911 call that he owned multiple semiautomatic rifles, according to an archived recording. Officers ended up recovering one firearm, a SIG Sauer 516 short-barreled rifle, sources said. The encounter left the woman injured, sources said, but the extent of her injuries was not disclosed. Altogether, the allegations were the basis of Foster getting booked at the Santa Clara County Main Jail on suspicion of domestic violence, making criminal threats, and possessing an assault weapon. He was released Sunday evening after posting $75,000 bail.