A four-alarm fire in Cambridge, Massachusetts, caused a building's roof to collapse Tuesday morning.
Heavy fire was showing when crews arrived at the 2-1/2-story building on Reservoir Street around 8 a.m. Cambridge fire said the blaze has since been knocked down.
The fire could have been a lot worse, but thanks to a construction crew that was working nearby, everyone got out.
"I saw a little bit of smoke coming out the back porch. I walked over, I saw flames," said Tiago Oliveira, one of those construction workers.
He and his crew jumped into action, calling 911 and knocking on doors. The four workers managed to wake up the three men inside the 2-family home, and they got out just in time.
"It went from maybe a foot and a half wide to a foot high, the flames... within minutes it took off," Oliveira said.
Acting fire Chief Gerard Mahoney said a "mayday" was called at one point when a firefighter became trapped inside. But he was able to get out of the home safely. He said a couple of firefighters suffered minor injuries.
The cause of the fire remains under investigation.