A firefighter sustained a minor injury and 20 people were displaced after a fire broke out at a Worcester home early Thursday morning, the Worcester fire department said.

The fire was extinguished by about 3:30 a.m., the department said in a tweet. A firefighter was evaluated at the scene but was OK and returned to work, Deputy Fire Chief Martin Dyer said.

The fire started on the home’s front porches, Dyer said.

The cause of the fire remains under investigation.

Globe Correspondent Caroline Enos contributed to this report.

Amanda Kaufman can be reached at amanda.kaufman@globe.com. Follow her on Twitter @amandakauf1.