An explosion at Bridgeport's Tradebe Environmental Services erupted on Friday when a driver delivering an oxidizer chemical opened a valve, igniting several explosions, fire officials say.

City officials said the surrounding air remains safe for residents, who were allowed to return Friday night after being forced to evacuate.

The scene remains active off Cross Street near the hazardous waste management plant. Fire, police and environmental crews are assessing the damage. Crews were also seen assessing water quality off Exit 30 at Lordship Boulevard in Stratford.

The city’s emergency management officials warned the public not to fish in nearby brooks due to high pH levels. They also said wearing a mask is no longer required.

“That testing has to be done. Right now, I would say that folks should be moving about with an abundance of caution, in respect to even basic drinking water,” said State Sen. Herron Gaston, of Bridgeport.

Gaston called Friday’s explosion one of the scariest events of his life.

“It reminded me of wartimes. You could see the fire and the thick smoke,” said Gaston. “People were running out and embracing each other in the middle of the roadway.”

Gaston is among those calling for federal and state investigations.

“This could have been much worse than what it was. We could have had the loss of life, we could have had the loss of an entire community that could have been blown out as a result of what happened there,” said Gaston.

Officials said three people were taken to the hospital – one for burns and two for smoke inhalation. Two have been released.

“We want to dig down to ensure there was no negligence and that this is something that could be avoided in the future,” said Gaston.

Several local roads remain closed.