PHILADELPHIA (CBS) — Officials say one of the children injured in the house fire in Olney last week has died.

Philadelphia Fire Department Captain Dixon announced today that the 11-month-old boy rescued from the house fire that broke out Thursday night on the 300 block of East Sheldon Street has died from his injuries.

The six-year-old boy injured in the fire remains in critical condition.

Officials said the fire had been put out quickly but there was already heavy smoke when crews arrived.

Fire commissioner Adam Thiel says first responders were there within five minutes and they found the two kids on the second floor.

They were transported both in critical condition. The six-year was taken to St. Christopher’s, while the 11-month-old was transported to Einstein.

The cause of the blaze remains under investigation.