A massive five-alarm fire in Brockton that caused minor injuries to three people and destroyed a home could have been even more devastating if it weren’t for fast reactions, according to the city fire chief and residents.

Nineteen residents who lived at the two properties, 35 and 37 South St., have been displaced, while two of them and a firefighter suffered exhaustion and were sent to an area hospital for treatment, Chief Brian Nardelli told reporters at the scene.

By the time Brockton firefighters arrived at 37 South St. around 3 a.m., eight residents had escaped from the flames, but some had to be rescued from behind the home, Nardelli said.

“We had guys breaking the fence and pulling them through the fence because the radiant heat was coming off that house,” he said. “They were trapped in the courtyard almost.”

One resident, Maria Rogers, owner of 37 South St., told WCVB she believes her dog saved her life, as the dog’s barks woke her up in time to get out unscathed physically.

“He (doesn’t) leave my side. Thank God for him,” Rogers said of her dog. “He was going crazy barking. I thought somebody was knocking at the door. I was like, ‘What is going on?'” I thought it was raining. Thank God for him. I got up hysterically.”

Emergency crews remained on scene throughout the morning, and the two-and-a-half story home at 37 South St., was torn down later in the afternoon.

Within minutes of arriving on scene, the Brockton Fire Department struck a fourth alarm before shortly increasing it to five. The heavy blaze quickly spread to neighboring 35 South St., and 11 residents in that home had escaped without injury, officials said.

Officials said they believe the bottom level of 35 South St. can be saved.

The Brockton Fire Department did not immediately respond to a Herald request for further updates Thursday evening.

The cause remains under investigation by Brockton police and fire and State Police assigned to the state Fire Marshal’s Office.