Ohio train derailment: Evacuation order lifted, residents can return home

Residents near the Ohio-Pennsylvania state line who were told to evacuate after tanker cars derailed in a fiery crash can return home after an evacuation order was lifted on Wednesday, officials said.

Air and water samples that were collected Tuesday have been deemed safe, according to officials.

Officials have urged East Palestine residents to follow a "Safe Return Traffic Plan" to ensure a seamless return to the northeastern Ohio village where the derailment occurred on Friday.

"We came together as a community and put safety first, avoiding what very well could have been a tragedy of epic proportions," Chief Keith Drabick of the East Palestine Fire Department said at a press conference on Wednesday.

The Ohio EPA will remain involved to oversee the long-term cleanup, working with Norfolk Southern and other contractors over the next several years -- aiming to ensure the air and water remain within safety thresholds.

Crews conducted a controlled release and burn of toxic chemicals from five of the derailed cars that were in danger of exploding on Monday afternoon, officials said. A large ball of fire and plume of black smoke could be seen billowing high into the sky from the smoldering derailment site in East Palestine as the controlled burn took place.

As of Monday night, a 1-mile mandatory evacuation zone had been in place around the site, according to East Palestine Mayor Trent Conaway.

East Palestine is home to roughly 4,700 residents, about half of whom had been warned to leave over the weekend before officials decided on Monday to conduct the controlled release.

About 50 cars of a Norfolk Southern Railroad train, traveling from Illinois to Pennsylvania, derailed in the village on Friday night at around 9 p.m. local time. Ten of the derailed cars were transporting hazardous materials, five of which contained vinyl chloride. No injuries were reported, officials said.

According to the National Transportation Safety Board, two videos show preliminary indications of mechanical issues on one of the car's axles. The train's emergency brake was activated after crews said an alarm went off, the NTSB said.

Efforts to contain a fire at the derailment site stalled on Saturday night, as firefighters withdrew from the blaze due to concerns about air quality and explosions.

Forced evacuations began in East Palestine on Sunday night and by Monday residents in a 1-mile by 2-mile area surrounding the site, which includes parts of Ohio and Pennsylvania, were ordered to evacuate immediately.

"The vinyl chloride contents of five rail cars are currently unstable and could potentially explode, causing deadly disbursement of shrapnel and toxic fumes," the office of Ohio Gov. Mike DeWine said in a statement Monday.

The controlled release and burn went "as planned," according to Pennsylvania Gov. Josh Shapiro.

"Thus far, no concerning readings have been detected," Shapiro said during a press conference on Monday evening, about three hours after the procedure began. "For now, out of an abundance of caution, Pennsylvanians who live within two miles of East Palestine, where this derailment occurred, should just continue to shelter in place this evening and keep your windows and your doors closed."

Crews monitoring air quality "have not seen anything" unexpected, according to James Justice of the U.S. Environmental Protection Agency.

"So far, so good," Justice said at the press conference. "And we're going to continue to monitor until the fire's out."

In a statement to ABC News, Norfolk Southern Railroad also called Monday's controlled release a success and said materials were burning off according to plan.

"We have been, and will continue, monitoring air quality with the Ohio EPA," the rail operator added. "Remediation work at the site can now safely continue.|

ABC News' Jianna Cousin, Alexandra Faul, Matt Foster, Melissa Gaffney, Teddy Grant, Darren Reynolds and Alondra Valle contributed to this report.