Cottrell Broadnax, 49, is charged with false imprisonment, assault with a firearm, being an ex-felon in possession of a firearm, carrying a loaded firearm and possession of a controlled substance, Alameda County District Attorney's Office spokeswoman Teresa Drenick said.
Broadnax has at least 14 prior felony convictions dating back to 1980, which could significantly increase his prison sentence if he's convicted, Dresnick said.
Oakland police said officers responded to Children's Hospital at about 3:30 a.m. Friday after receiving a report that Broadnax was holding a nurse hostage at gunpoint.
They said Broadnax surrendered after police formed a perimeter of patrol rifle officers. No one was injured in the confrontation.
Hospital spokeswoman Erin Goldsmith said that when Broadnax entered the hospital, he appeared to be disturbed or disoriented but did not have his gun drawn as he strode past the trauma center's front desk.
Goldsmith said only eight minutes elapsed between when Broadnax entered the emergency room and the time Oakland police took him into custody.
Oakland police said Broadnax was also arrested on suspicion of attempted carjacking because he reportedly jumped on the hood of a woman's car at a nearby gas station just before the hospital incident.
But Broadnax hasn't been charged with attempted carjacking, Dresnick said.
Broadnax's prior convictions include false imprisonment, assault with a deadly weapon, grand theft, robbery and burglary.
He is scheduled to appear in court in Oakland at 2 p.m. today.