Federal workplace safety authorities are investigating a concrete floor refinishing project in a Missouri home that took an explosive turn last Thursday (May 9).

Local authorities say that two professional painters from Huddy Painting of Troy, MO, were sealing and coating the basement floor of a St. Peters home without adequate ventilation when a chemical explosion occurred.

No one was injured.

KTVI / Fox News

Painters were working in the basement of the St. Peters, MO, home, when inadequate ventilation and an unsecured hot water heater led to a chemical blast.

While the furnace had been secured, the hot water heater was reportedly overlooked.

When the heater kicked on around noon, it ignited the flames, caused a flash fire and an explosion, Scott Freitag, assistant fire chief with the Cottleville Fire Protection District, told local television reporters.

Five people and three dogs were in the home during the blast, reports said.

Huddy Painting, a full service residential and commercial interior and exterior painting company that serves the St. Louis area, did not return a call Wednesday (May 15) for comment.

Homeowner: ‘Felt Like an Earthquake’

“[Sparks] were coming from the basement, and then it just felt like an earthquake,” the homeowner, Pam Smith, told a local Fox News affiliate, KTVI.

“We are just so glad to be alive,” she said.

Smith had hired the contractor to refinish the floor of her three-bedroom ranch home following water damage.

Home Not Livable

The home suffered structural damage in the blast and is condemned, reports note.

Scott Freitag / Cottleville Fire Protection District

The explosion caused the garage door on the ranch-style home to buckle.

One wall of the home was blown out approximately 18 inches, the roof over the porch was lifted off its columns and then set back down and the garage door buckled, according to Freitag.

“It’s significantly damaged; it’s not livable,” Freitag told the St. Louis Post Dispatch.

OSHA Launches Investigation

An Occupational Safety and Health Administration official confirmed that the office in St. Louis is investigating the incident, but noted that the agency could not comment further on the case.

Freitag told D+D News that he had been contacted by OSHA. Huddy Painting does not have a record with OSHA, according to a review of OSHA's online database.