The family members of a U.S. citizen who was taken into custody by federal agents in downtown Los Angeles on Tuesday are demanding answers as she was detained while on her way to work. 

Andrea Velez, a Cal Poly Pomona grad working in merchandising at a shoe company, had just been dropped off by her mother and sister for the workday when they saw her being taken into custody, adding they had barely even driven a block before the arrest began.

"They didn't have vests that said ICE or anything," said Velez's sister Estrella Rosas. "Their cars didn't have license plates."

She says that her mother was driving away when she looked in her rearview mirror at what was described by police as immigration enforcement.

"In the rear mirror she saw my sister was kinda, like, attacked from the back and she was already on the floor," Rosas said.

Video shows a growing crowd of onlookers yelling as officers surround the 32-year-old woman. Her family members were too scared to get out, as Rosas' mother has residency but not full U.S. citizenship. 

They're also worried that Velez may have been holding pepper spray, which they say she always carries in her hand when walking downtown, when agents approached her. 

Witnesses told CBS News Los Angeles that no one asked for her identification, but her family believes that it was nothing she actually did that led to her arrest, but rather the way she looks. 

"Just because of the color of our skin, they think we're criminals," Rosas said. "My sister was there, so they were like, 'Oh, she looks Hispanic, so let's take her too.'"

As of Tuesday night, they have still not been able to find out where Velez is being held and are worried it could be days before they finally do. 

CBS News Los Angeles has reached out to the United States Immigration and Customs Enforcement for information on Velez's arrest but has not yet heard back. An inquiry was also made asking how agents check a person's status when they first come into contact, and how they find the people they're targeting in enforcement operations. 

Some of the video circulating online, showing Velez's arrest, also shows a group of Los Angeles police who appear to be aiding federal agents in the immigration operations. 

Later Tuesday, officers told CBS News Los Angeles that they were called to the area after receiving a 911 call reporting a kidnapping at the location. When they arrived, they say that they saw that a federal immigration operation was underway and stayed to maintain peace because they were concerned by the growing crowd and the federal agents.