(KRON) -- An Oakland man is facing 12 felony charges after allegedly firing an assault rifle during an attempted robbery of a local market and, in a separate incident, violently robbing an elderly woman, Alameda County District Attorney Ursula Jones Dickson announced Wednesday. On Aug. 19, prosecut ors said Derrick Walker, 28, walked into Sky Market on 14th Avenue in Oakland and demanded money. During the attempted robbery, Walker “fired several rounds” from his assault rifle, the DA’s office said. No one was injured in the incident. Eight days later, on Aug. 27, Walker allegedly assaulted an elderly woman on Eighth Avenue in Oakland. Prosecutors said Walker knocked the woman to the ground, causing injuries, while stealing her shoulder bag and its contents. Convicted murderer among 2 arrested in Vallejo gas station burglary Walker was arrested in Oakland on Sept. 10. On Tuesday, the DA’s office charged Walker with attempted second-degree robbery and two counts of assault with a semiautomatic weapon, along with several counts for possession of a gun and ammunition by a felon in connection with the first incident. He was also charged with second-degree robbery and more counts of firearm and ammunition possession in connection with the second incident. Prosecutors said Walker has three prior convictions for robberies that occurred in 2021 and 2023. He remains in custody without bail. ...read more read less