I just got an email from JFX. They have more video footage of Britney Spears in an ambulance outside her house. Jayden James was placed inside too. Here is what they know:

We've got a video clip of tonight's craziness with Britney. You can see glimpses of Britney on the gurney inside of the ambulance and the mayhem that ensued once we arrived at Cedars. We'll be posting more pics and more video as the day continues and we'll be following up with Britney's condition. As of right now, here's who's keeping Britney company at Cedars:Britney's youngest son Jayden James was also taken to the hospital, where we saw him be carried in but otherwise, looked healthy.
Britney's father Jamie has also arrived on the scene.
We also know that Brit's former confidant, Sam Lutfi is also on scene.

Story developing --
UPDATE: OH MY GOODNESS!! People Magazine is claiming that Britney had the kids, the cops were called in, they noticed she was under the influence and the madness began. They took her to the hospital for an evaluation.

"While officers were on the scene, they observed Ms. Spears under the influence of an unknown substance," Lee added. "She is now being taken in for an evaluation, more than likely to a hospital. There were no reported injuries to anyone involved including the children."