Five young children — including four siblings — were killed in an early-morning blaze at an Erie, Pa., day-care center Sunday, according to emergency officials and local news reports.

Erie Fire Chief Guy Santone told NBC News the children ranged in age from 8 months to 7 years.

Erie government officials said in a Facebook post that firefighters were able to rescue seven people from the 1:15 a.m. blaze but couldn’t save the five little ones.

Two older boys were able to escape by climbing onto a first-floor roof and then to the ground, according to goerie.com, which added that the owner of the center was in stable condition at UPMC Mercy hospital.

The address of the fire comes back to Harris Family Daycare, according to the local chamber of commerce.

A woman interviewed by goerie.com was identified as the grandmother of four of the dead children. She said the four siblings were at the center because their parents were working overnight.

“So we are all at a loss, trying to figure out how this happened,” the woman, Valerie Lockett-Slupski, told the Web site.

Fire officials have not determined the cause of the blaze.

“Our prayers go out to the families involved in this tragic fire, to the neighbors, and to our firefighters,” Erie city officials said in their Facebook post.