There were a whole lot of police/fire/ambulances at the scene, but there was no panic. From what I gather, one floor has been evacuated (1st) and everybody is being checked out (but very few seem to need medical attention). Apparently 10 people have been taken to hospital due to inhalation related problems.
More details to follow, when I hear more...
I've since heard several conflicting reports... One is that 4 people were taken to hospital, 7 people were treated on the scene, 150 people were evacuated and three floors of the hospital had been shut down. Another says that 22 people were taken to hospital and the entire building was evacuated.
According to the rumour mill, the "unknown chemical" was possibly sulpherous. Another story is that two guys came into the hospital, went up to reception, smashed a bottle/jar of some chemical on the floor and ran off.
Still looking for more info...
Straight from the horse's mouth (or the lab manager's mouth as the case may be): Apparently someone in the hospital (most likely a disgruntaled patient) threw some kind of tantrum and dumped a whole lot of random chemicals on the floor (a combination of code grey and code yellow for those in the know). While no-one is exactly sure at this stage what the chemicals were or why a hissy fit was had, the chemicals burnt a hole through the carpet and released a whole lot of noxious fumes which were then sucked up into the air-con and ventilation system.
Latest estimate was about 10 people taken to hospital.