Amanda Bynes

Amanda Bynes is currently hospitalized on a 5150 hold ... after starting a small fire in the driveway of someone's home Monday night ... TMZ has learned.

Law enforcement sources tell us the fire department responded to the home in Thousand Oaks, CA last night ... and called the sheriff's department after finding Amanda standing in the driveway next to the campfire.

Sheriff's deputies questioned Amanda about what she was doing, and why she was doing it -- and based on her answers they determined she needed to be hospitalized on a 5150 hold.

Story developing ...

Amanda Bynes

6:15 AM PT -- Bynes just arrived to court ... wearing an aqua-colored wig ... with black baggy pants, a black tank top and sneakers. Judge is gonna LOOOOVE this.

The judge has denied cameras inside the courtroom ... so we'll UPDATE this post with info as soon as it happens. Keep refreshing for updates. Amanda Bynes' showdown with the NYPD is coming to a head this morning in court -- after the actress was arrested for allegedly throwing a bong out of her apartment window back in May.

Bynes is expected to be present in court today for a hearing in her case. As we reported, she was arrested on charges of reckless endangerment, tampering with evidence, and weed possession following the alleged Manhattan bong-tossing incident.

According to police, Amanda threw the bong out of her window before they arrested her, but she has denied the accusation ... in fact, she says the arresting officer sexually assaulted her by slapping her vagina.

She also said cops entered her apartment illegally.

The hearing is scheduled to begin at 6:30 AM PST/9:30 AM EST ... and if it's anything like Bynes' last wacky wig court appearance, it should be interesting.