The National Transportation Safety Board (NTSB) has scheduled a 4 p.m. news conference on Thursday to update its investigation into the Realty Building explosion in downtown Youngstown Wednesday night.

Investigators of the NTSB pipeline and hazardous materials division arrived downtown late Wednesday.

Thursday's news conference will be conducted at the Holiday Inn, Boardman.  The briefing will be streamed live on WFMJ.COM and our Facebook page.

Enbridge Gas Ohio, formerly Dominion, issued the following statement regarding the development:

The National Transportation Safety Board (NTSB) will be taking the lead in this investigation and Enbridge Gas Ohio likely will be asked to assist as a party to the investigation. Federal regulations prohibit us from commenting on the investigation.

Youngstown Mayor Tito Brown said the State Fire Marshal and Enbridge Gas Ohio have finished their investigations at the site and NTSB personnel will take over.

"We don't know what they're looking for but since natural gas moves it falls under transportation, so that's a new one for us," Mayor Brown said. "We had some engineers looking at the building today as well and there's a tighter perimeter but we're going to have security here for the next few days."

Mayor Brown says fencing will be put up around the building soon.

The structural integrity of the building is still in question.

"That's the $1,000 question," Mayor Brown said. "The debris is in the bottom, until you clear the debris out, you don't know if cross beams are gone or if anything is bent or leaning."

The explosion at the Realty Building, which houses Chase Bank and apartment units, happened at 2:45 p.m. Tuesday. The blast led to evacuations of many buildings in downtown Youngstown and routes into the city being shut down for a time.

Akil Drake, a 27-year-old Chase Bank employee was killed in the explosion. His body was recovered from the debris around 1 a.m. Wednesday.

Seven others were taken to the hospital and as of Wednesday morning, one person was still in critical condition. Three people are in stable condition and another three were released from the hospital.

The Stambaugh Building and Realty Building remain closed indefinitely.