Sources with direct knowledge tell us, Woz gave a speech Wednesday in Mexico City at the World Business Forum, after which he told his wife he was "feeling strange." He then started exhibiting symptoms that alarmed his wife, who said he needed to go to the hospital.

We're told the 73-year-old cofounder of Apple resisted, saying he'd be OK, but his wife persisted and ultimately insisted he go to the hospital.

At the time of the post, we're told Steve is in the E.R. at a Mexico City hospital, where doctors are performing tests.

Several people from Steve's team are flying from the U.S. to Mexico City on a private jet, to see firsthand what is going on with him and take him back to the U.S. for further treatment if that's necessary.

Woz has been traveling a lot lately, but it's unclear if fatigue played a part in the medical emergency.