Police say the 26-year-old woman was walking at about 12:30 a.m. Saturday when the men approached her near 11th and Market streets in West Oakland. One of the men had a gun and the pair assaulted the woman behind a liquor store, authorities said.
They forced her to take money from an ATM and then drove to her nearby apartment, where they assaulted her two female roommates, ages 30 and 29, police said.
Authorities say none of the victims knew the suspects. They are described as two men, between 20 and 30 years old and about 6 feet tall.
Oakland police sent out a community alert on the attack Tuesday morning. Officer Jeff Thomason said the department may need to review its policy on notifying the public of sexual assaults given the notification on this attack came days after it occurred.
"We are going to review the process of notifying the public and hopefully change how we put it out in the future," Thomason said.
A $30,000 reward is being offered for information about the assaults. Anyone with information can call police investigators at 510-238-3641, or Crime Stoppers at 510-777-8572 or 510-777-3211.