A fast-moving, second-alarm fire that damaged a home in Worcester late Tuesday night claimed the lives of two residents and displaced seven others, according to authorities.

Two adults living on the first floor of the triple-decker structure at 3 Hancock St., became trapped inside as the fire started to spread from the unit’s living room area and died in the blaze, Worcester Assistant Fire Chief Adam Roche told reporters outside the home Wednesday.

Roche did not identify the victims but said they were both adults. He called the incident “tragic for the city of Worcester” and added that the department is keeping the family of the victims in its hearts and prayers.

“This is a difficult fire for the Worcester Fire Department,” Roche said, “but we are a resilient group and our firefighters did a valiant job. They really leaned back on their strategies and tactics to try and get a better outcome here. The fire conditions were just so advanced on arrival.”

Firefighters arrived on scene at the home on Hancock Street, off of Main Street and near Clark University, after receiving a dispatch around 11:30 Tuesday for a reported building fire with people trapped inside, Roche said.

Four adults and three children across the second and third floors evacuated safely as firefighters encountered heavy fire on the bottom level. The blaze rose to two alarms before it came under control within 15 minutes, Roche said.

The home seemed to have been “appropriately maintained,” Roche said. He highlighted how the city is filled with many triple-decker homes which often contain balloon-framed construction, making it a challenge to extinguish fires in such structures, he said.

“That allows fire to get into void spaces and spread throughout the house very quickly. In order to extinguish these fires, we have to get into those void spaces,” Roche said. “This particular fire was so well advanced on our arrival that it proved very difficult for the residents on the first floor to escape.”

The fire remains under investigation.