Some of the victims are uninsured and face mounting hospital bills.
Children's Hospital Colorado said it would use donations to cover the medical expenses of the uninsured. For those who do have insurance, the hospital said it will waive all co-pays for shooting victims.
HealthOne, which owns the Medical Center of Aurora and Swedish Medical Center, also said it will limit or eliminate charges based on the individual circumstances of the patients.
There's no word yet on what the other two hospitals plan to do.
See an outline of events and facts surrounding the Colorado theater shooting
The news comes as the first of what will be many memorial services was held on Wednesday in Aurora. It was for 51-year-old Gordon Cowden - the oldest of the victims - who was watching the movie with his teenage kids. They were not hurt.
New details are emerging about the suspect in the shooting rampage. James Holmes took a key oral exam in early June that was part of his PhD program. According to ABC News, he failed, and then hours later, he bought a high-powered rifle that became part of his cache.
Holmes is accused of methodically stockpiling weapons and explosives at work and at home that police say he used to kill 12 people and wound 58 more at a midnight showing of "The Dark Knight Rises" Friday. Police say he also booby-trapped his apartment with the intent to kill police officers.
Holmes spent a year in a small neuroscience doctoral program, surrounded by scientists and roughly three dozen classmates, delving into the inner workings of the brain. Authorities say while he was studying neuroscience, Holmes began shopping for firearms.
Read statements from public officials about the Colorado theater shooting
He filed paperwork to withdraw from the program three days after his oral exam, but never provided a written explanation for his departure. Experts say that failing the test may have triggered an underlying mental illness.
"All of those things could actually make dormant schizophrenia come out, and come out relatively quickly," said Marisa Randazzo, a psychologist who studies targeted violence.
Holmes remains in solitary confinement in Arapahoe County jail. Officials are trying to figure out how Holmes learned how to use and practiced using the weapons that he allegedly fired. Authorities say he acted like a focused marksman in the movie theater.
Glenn Rotkovich, owner of a private Colorado gun range outside Denver, said Holmes applied to join the range in late June. But after hearing Holmes' "bizarre" voicemail message, he rejected him as a member, concluding that there was something wrong with him.
"I flagged him to people and said, if he shows up, I don't trust him," Rotkovich said.
Since his arrest, Holmes has been displaying odd behavior, beginning with his Monday court appearance where he looked dazed and disoriented.
Sources tell ABC News that Holmes has been spitting at jail officers so frequently that at one point, he was forced to wear a face guard.
Some observers wondered if Holmes was being medicated, but officials say he was not on drugs. Experts say he may be in the grips of a "psychotic episode," exhausted from stress - or simply faking it.
View photos from the scene of the shooting at an Aurora, Colorado theater
ABC News and the Associated Press contributed to this report.
