Connecticut Gov. M. Jodi Rell has signed an executive order banning state power plants from conducting the type of pipe cleaning procedure blamed for a fatal explosion in February.

Rell issued the order against gas blows Wednesday, a day after announcing it at the recommendation of a state commission she created to investigate the Feb. 7 blast at the under-construction Kleen Energy Systems LLC plant in Middletown.

The blast killed six workers and injured 50 others.

Authorities say the explosion was caused when something ignited natural gas and air during a gas blow, in which high-pressure flammable gas is blown through pipes.

The U.S. Occupational Safety and Health Administration has imposed $16.6 million in fines against companies involved in the explosion. The fines stem from claims of 371 safety and workplace violations.