ROCHESTER, Pa. (KDKA) – The whiffs of chlorine can still occasionally be detected with the sensitive nose in Rochester, but the Department of Environmental Protection says there is no risk.

It has been three days since the former Pool Doctor-Beaver Alkail Products site on the Ohio River’s edge in Beaver County caught fire.

Investigators believe the building’s collapsing roof caused a mixing of chemicals that erupted in flames.

When firefighters realized what they were dealing with, “part of our fire fighting tactics were to contain it,” says Rochester VFD Chief Michael Mamone III.

WATCH: KDKA’s John Shumway report live

Mamone says the water from their hoses caused the formation of a chlorine plum that prompted a shelter in place recommendation in Rochester. But he says the alternative would have been a possible spread of the fire to the adjacent building which contains similar chemicals.

Chief Mamone says, “The problem still exists in that there is still a building down there that is in demolition mode that the DEP is trying to clean up, and this potentially could happen again. But we have a plan in place to take care of those problems.”

Beaver County Emergency Service Deputy Director Kevin Whipple agrees.

“From what I saw Saturday evening, they have done a lot of work, and residents should be reassured they are doing everything they can to mitigate the problem,” he says.

“They” being Michael Baker International and DEP.

(Photo Credit: KDKA)

When the building partially collapsed in late June, the state moved in with a Hazardous Site Cleanup Act response and brought in Michael Baker to do the work.

Whipple says there are significant questions about the site because, “The property owner has not reported any chemicals for several years so that’s a problem on their end.”

He says the state and first responders were surprised by what they found.

Since the fire was put out, the contractor has been working around the clock to remove chemicals and put them in water to neutralize them.

(Photo Credit: Kevin Kunselman)

A statement from the DEP says the complete cleanup could take a while, saying in part:

“There are many unknowns with the site, including the types, amounts, and compatibility of chemicals within the buildings. Many of these chemicals were unlabeled and their containers compromised. Both buildings on site are dilapidated with collapsing roofs and unsafe for entry, further complicating the remediation and waste removal.”

Around-the-clock cleanup will continue until at least Wednesday with further work continuing for weeks.