PROVIDENCE, R.I. — A blaze that burned five school buses here on Thursday night is under investigation, authorities said.

Chief Kevin Jutras of Providence Fire Department told The Boston Globe that crews responded to a First Student bus yard at 3 Riacom Way shortly after 7:30 p.m., and upon arrival, at least one bus in the yard was engulfed in flames.

Jutras added that one firefighter was injured as crews worked for 20 minutes to knock out the blaze.

Steven Pare, the city's public safety commissioner, told WPRI that while the cause of the fire remains under investigation, authorities are considering it suspicious at this time.

School bus drivers contracted with First Student began a bus strike Sept. 27 after negotiations over retirement benefits with the company fell through, WPRI reports. The strike has left more than 9,000 students without transportation to and from school, according to the news source.

Teamsters Local 251, the organization representing the school bus drivers in the strike, said on its Facebook page that both the organization and the drivers "condemn the property damage," and they are grateful no serious injuries were reported.

The organization added that once both parties reach an agreement, the drivers will return to their bus routes.

Providence Mayor Jorge Elorza told WPRI that the while the incident coincides with the strike, city officials are still planning to move forward with a full investigation.