The following update was provided by Alexis Newell, a Monrovia spokeswoman.
As of now, the HazMat incident has stabilized and all emergency resources have been released.
A manufacturing company (Air Logistics) on Railroad Avenue was batch mixing three chemicals and at some point there was an adverse reaction causing the chemicals to heat up and off gas into the air. The chemicals were never unstable, but were superheated.
The chemicals identified were: Cyclo Aliphathic resin, Boron trifluoride, and Ancamine
Symptoms from employees who reported feeling ill were chest pains, asthma, dizziness, nausea and vomiting.
Monrovia was able to avail itself of many of the local resources in the area including Fire mutual aid, Health HazMat and AQMD and it is business as usual here.----
Updated 2:20 p.m.
Monrovia Fire, Health HazMat, and the Air Quality Management District continue to investigate the exposure to a chemical that made employees and residents in the 100 block of Railroad Avenue sick today.
Smoke was reported coming out of the vents at AirLogistics, a company at 146 Railroad Avenue, at 11:05 a.m. An unknown resin was off gassing at the facility, said Alexis Newell, a spokeswoman with the city of Monrovia.
The authorities are on the scene trying to identify the chemical and treat patients, she said.
"Approximately 200 people were exposed to the chemical gases, 45 became symptomatic, reporting dizziness and other symptoms," Newell said. "Nine have been taken to local area hospitals, two with immediate needs and IV support."
Officials are encouraging all people who are experiencing symptoms to be transported to area hospitals, but is not mandatory. No firefighters who responded to the scene have been exposed.
Myrtle Avenue from Duarte Road to the 210 Freeway has been temporarily closed to enable ambulances to come in and out of the area, she said.
Authorities are asking that people in the area stay inside until the hazardous material can be identified and contained.
Broadcast reports have pointed to an air conditioning business in the area as the source of the problem, reported City News Service.
Some residents and employees in the air reported feeling ill, so a shelter was set up, Monrovia spokeswoman Alexis Newell told City News Service.
"Hazmat crews are currently on scene to identify the unknown chemical ... and treat patients feeling ill,'' Newell said.
The section of Railroad Avenue bordered by California, Myrtle, Pomona and Duarte avenues has been evacuated due to a possible hazardous waste spill.
Authorities have set up temporary shelter for employees and residents in the 100 block of Railroad.
HAZMAT crews are on the scene investigating.
Patch will update this story as more information becomes available.