The fire was reported around 10:30 a.m. at 1401 King Road in West Whiteland Township, Pa. at the Johnson Matthey plant.
Patty Mains, a spokeswoman for Chester County Department of Emergency Services, says the plant itself was evacuated, as well as some houses in the area.
That order was then cancelled around 2:10 p.m.
The view from Chopper 6 HD showed a number of people standing outside the building while firefighters worked to douse the flames.
One person was injured. The victim was taken to Crozer Chester Medical Center in an unknown condition.
The DeCorte sisters, who live near by, tell us they heard several explosions.
"It was louder than thunder. it honestly sounded like a tractor trailer just tipped over and then a loud boom," said Kristen DeCorte.
Then, they received a "reverse-911" call telling them to evacuate.
"it was a little nerveracking for my grandma because she's older and for me, I have a newborn and a 6-year-old so I was like 'How bad is this?" said Amanda DeCorte.
"Nothing ever really happens here, it was odd, it was really odd," said Kristen DeCote. "I didn't even know that plant was over there."
Once the fire was out, we spotted employees inspecting the damaged hydrogen containers.
The fire marshal is investigating the cause of this fire.
Adding to the concerns on Wednesday afternoon was an emergency alert which called for a countywide evacuation, but that was never the case. Chester County emergency management officials told Action News that, as far as they know, the system worked correctly.
On its website, Johnson Matthey bills itself as a speciality chemicals company focused on catalysis, precious metals, fine chemicals and process technology.