Authorities responded Thursday morning after several explosions at a chemical plant in Newburyport, Massachusetts, blew a hole through the roof and forced the building to be evacuated.

Fire officials said they responded to SEQENS, formerly PCI Synthesis, at 9 Opportunity Way after receiving a call at around 4:30 a.m.

They "made entry to the building and encountered heavy black smoke so they retreated. When they got outside, they heard a series of three explosions," Newburyport Fire Department Deputy Chief Stephen Bradbury said.

The explosions, which blew a 5-foot by 8-foot hole in the roof, prompted a quick evacuation of the building.

Bradbury said the hole in the roof was not unusual.

"It's designed like that. It relieves pressure. That's what the vessel did so as far as we knew, it worked the way it was supposed to until we find out more information from the state fire marshal's office," he said.

Several employees, believed to be fewer than 10, were inside the building when the incident took place but no one was injured, fire officials said. One employee at the plant was evaluated by emergency medical services but declined transport to a hospital.

A Tier 2 hazardous materials incident was declared, which activates a regional team of specially-trained professionals. Hazmat teams initially made entrance to the building with a robot and conducted numerous tests, which determined that there was no danger to the surrounding community.

State police earlier said that a bomb squad had responded to the scene.

The company said in a statement on Twitter that it is working with local authorities on the investigation.

We're working diligently with local authorities after reports of an explosion at our Newburyport facility. All employees on site were safely evacuated; no injuries reported. We will provide more information when we learn more. Thanks to police & fire for their quick response. — SeqensCDMO (@Seqens_CDMO) February 13, 2020

According to federal records the NBC10 Boston Investigators reviewed, OSHA has levied initial fines totaling a combined $150,016 against the company since 2010 and charged it with a combined 18 serious safety violations, although PCI Synthesis was later found responsible for only 13 serious violations and five lesser violations after reaching settlements with federal safety officials. It paid a combined $84,730 in fines as a result.

Violations in 2015 pertained to employees’ exposure to hazardous material and a federal inspection last January resulted in six violations related to its safety procedures, its plan for handling chemicals and requirements to conduct a hazard analysis.

According to OSHA statutes, those recent violations related to safety regulations for “preventing or minimizing the consequences of catastrophic releases of toxic, reactive, flammable or explosive chemicals.”

In 2006, the chemical manufacturer was also fined for violating hazardous waste laws, according to a release from the Environmental Protection Agency.

The company said in a statement Thursday afternoon that the incident only affected one production suite, and 85% of the building was unaffected. Local authorities are continuing to assess the facility and the company has not been allowed back inside yet.

Three businesses in immediate proximity to the plant were not allowed to open on Thursday morning but have since reopened.

The cause of the explosions has not yet been determined.

"PCI Synthesis is fully regulated and inspected by OSHA and EPA as well as other agencies to ensure the utmost safety and environmental standards in all of our facilities," the statement continued. "Our Environment, Health and Safety (EHS) staff works closely with all of those agencies on a continuous basis. We have an excellent environmental and safety record which we work hard to maintain and are very proud of. "