Lindsay Lohan has reportedly been placed in isolation following a "hysterical fit".
The 24-year-old actress - who started her sentence at the Century Regional Detention Facility in Lynwood, California on Tuesday - is said to have broken down in tears, screaming at wardens, forcing them to take her away from other inmates.
Newly-released Cheryl Presser, 43, told the Daily Mirror newspaper: "She is in with the killers and she has only been let out for hour-long breaks, and during those she was locked down to a table.
"On Friday, Lindsay got put on lockdown. While some of us got two hours to go to the yard, or the TV room, Lindsay was on total lockdown.
"She had a hysterical fit, crying and yelling so she got put in isolation."
Another former inmate claimed Lohan was upset because other prisoners had been poking fun at her by calling her 'Firecrotch', the nickname she was infamously given by oil heir Brandon Davis.
The source said: "She was just sitting in her cell staring straight ahead. Sometimes wailing, but mostly just sitting.
"Some of the inmates in our ward, some of the tougher ones, were yelling 'firecrotch' at her.
"They just started chanting it at her. Lindsay didn't say nothin'. She was crying though."
It is believed the actress was briefly admitted to the nearby Lofts Medical Centre and checked over following the incident.
Presser also revealed the 'Mean Girls' star has failed to win over other inmates because her constant crying keeps them awake at night.
She said: "The wards are cold and smelly - they stink. The air conditioning is turned up so high that you can't sleep because of the cold. Inmates try and shove the air vents full of toilet paper to stop the air coming out, but it doesn't work.
"Lindsay would lie there shivering all night, crying and trying to cover her face with her hands. Her wailing was keeping everyone awake."
Lohan is expected to serve less than 14 days of the 90-day sentence she was given for breaching the terms of probation set for her 2007 driving under the influence (DUI) conviction.