Two of the four workers injured in an explosion and fire at a biofuels plant in Ascension Parish last week have been released from the hospital.

An unnamed worker was discharged from Baton Rouge General Regional Burn Unit on Tuesday morning after spending five nights in the hospital following the Thursday night explosion at the Renewable Energy Group plant in the Geismar industrial complex, said Meghan Parrish, a Baton Rouge General spokeswoman.

Two other workers injured in the blast remain at the hospital. One remained in serious condition Tuesday, while a second worker was listed in good condition, Parrish said.

The fourth worker injured in the explosion was released Friday.

The explosion at the plant occurred around 11 p.m. Thursday night as workers performed maintenance on a hydrogen line, according to parish sheriff’s deputies. The blast came as the plant was undergoing repairs after an April 2 explosion injured two workers and shut down production at the facility, which manufactures biodiesel, renewable naphtha and liquefied petroleum gas.

Among those injured in the blast Thursday was Nick Matassa, the son of Kenny Matassa, a Gonzales city councilman, longtime parish government employee and candidate this fall for parish president. Officials have not identified the other three workers and Parrish said Tuesday that for privacy reasons she could not identify the workers or say who remained in the hospital.