A sixth person has died from the massive explosion earlier this month at a Connecticut power plant, The Hartford Courant reported Friday.

The patient had been in critical condition at a Hartford hospital since the Feb. 7 blast, which originally killed 5 and injured 27 others.

The Kleen Energy Plant, which was being built in the college town of Middletown, blew up during the first test of its natural gas-fired generating system. Flames were seen shooting from a pipeline as a fireball lit up the sky and a huge plume of smoke hung over the scene.

Local fire officials and federal authorities are still investigating what caused the explosion, which was so powerful it alarmed residents who heard the boom and felt tremors in their homes miles away.

– Fox News and the Times of London contributed to this report