In both robberies, victims were approached from behind by a group of people who struck them with an unknown object and stole their belongings, according to police.
The first robbery was reported at about midnight April 28 near the intersection of Shattuck Avenue and Center Street. Another was reported at 8:14 p.m. on May 6 in the 2500 block of Benvenue Avenue, police said.
The suspects have been described as a group of two Hispanic or black men and two Hispanic women.
One of the men was described as being in his 20s, about 5 feet 10 inches tall with a thin build, and was wearing a dark shirt and blue jeans. The other man was described as being in his late teens or early 20s, about 5 feet 6 inches tall with a medium-to-heavy build, and was wearing a white T-shirt and dark jeans.
The women are both in their late teens or early 20s and about 5 feet 3 inches tall. One has a thin build and was wearing a light blue or gray shirt and denim jeans, and the other has a medium build and was wearing a dark jacket and denim jeans, according to police.
Police are advising residents to remain aware of their surroundings. Items like iPods, cell phones and headphones limit awareness, and are also items thieves focus on to steal.
Anyone with information about these robberies are asked to contact the Police Department's robbery detail at (510) 981-5742 or the non-emergency number at (510) 981-5900. Callers wishing to remain anonymous can call the Bay Area Crime Stoppers tip line at (800) 222-TIPS.