Workers describe witnessing deadly steel factory explosion

PLEADED NOT GUILTY. >> INCREDIBLY TRAGIC. TRAGIC. ALL OF IT. >>> NONOW TO. >>> NOW TO PENNSYLVANIA WHERE THE STEEL L PLANT. THE STEEL PLANT EXPLOSION HAS KILLLLED TWO PEOPLE. NEW QUESTIONS TONIGHT ABOUT WHAT CAUSED IT AND WHAT. CAUSED IT AND WHAT ONE EMPLOYEE TELLS US ABOUT THE MOMENT. ONE EMPLOYEE TELLS US ABOUT THE MOMOMENT THEY FELT THAT. US ABOUT THE MOMENT THEY FELT THAT BLESSED. THEY FELT THAT BLESSED. ADRIENNE BROADDUS. ADRIENNE BROADDUS REPORTS. >> Reporteter: >> Reporter: TONIGHT, DEVASTATING DAMAGE SEEN FROM. ABOVE AFTER THIS MASSIVE EXPLOSION AT A U.S. STEEL PLALANT. A U.S. STEEL PLANT AS INVESTIGATORS WOWORK TO FIND THE. WORK TO FIND THE CAUSE. >> WE'RE N NOT GOING. >> WE'RE NOT GOING TO SPECULATE. WE'RE E GOING TO LET. WE'RE GOING TO LET THE PEOPLE DO THEIR WORK AND SUPPORT T THEM. THE PEOPLE DO THEIR WORK AND SUPPORT THEM AND THAT IMPORTANT. WORK AND SUPPORT THEM AND THAT IMPORTANT JOJOB. >> Reporter: OFFICIALS SAY THERE WERE NO WARNINGS. OFFICIALS SAY THERE E WERE NO WARNINGS THAT INDICATED ANY. WERE NO WARNINGS THAT INDICATED ANY PROBLEMS AT THE. FACTORY. >> ROUTINE MAINTENANCE IS WHAT. >> ROUTINE MAINTETENANCE IS WHAT THEY WERE PREPARING.

MAINTENANCE IS WHAT THEY WERE PREPARING FOR. I THINK IT WAS. THEY WERE PREPARING FOR. I THINK IT WAS ACTUALLY GOING TO. ACTUALLY GOING TO HAPPEN NEXT WEEK. >> Reporter: ANDREW. HAPPEN NEXT WEEK. >> R Reporter: ANDREW MacY HAS WORKED AT. R. THE STEEL PLANT FOR 44 YEARS. >> THERE WAS A VERY. 44 YEARS. >> THERE WAS A VERY LOUD BANG. LOUD BANG. WE LOOKED TO OUR LEFT THINKING THAT. WE LOOKED TO OUR LEFTFT THINKING THAT ON THE MAINLINE OF. ON THE MAINLINE OF OUR RAILROADS THE TWO ENGINES S COLLIDED. OUR RAILROADS THE TWO ENGINES COLLLLIDED HEAD-ON. AND THEN AS. TWO ENGINES COLLIDED HEAD-ON. AND THEN AS WE TURNED TO OUR. HEAD-ON. AND THEN AS WE TURNED D TO OUR RIGHT, WE SAW A. WE TURURNED TO OUR RIGHT, WE SAW A PLUME OF BLACK SMOKE. PLUME OF BLACK SMOKE AND IMMEDIATELY Y THERE WAS SILENCE.

AND IMMEDIATELY THERE WAS SILENCE. >> Reporter: HERE IS. THERE WAS SILENCE. >> Reporter:r: HERE IS VIDEO OF THE PLANT. VIDEO OF THE PLANT FROMOM 2019. YOU SEE THE FIVE. SMOKESTACKS AT THE CENTER. AND THIS IS WHAT IT. CENTER. AND THIS IS WHAT IT LOOKS LIKEKE AFTER. LOOKS LIKE AFTER MONDAY'S BLAST. POPORTION OF THIS. PORTION OF THIS BUSTLING W WORKSITE NOW A MASSIVE. NOW A MASSIVE CLEANUP OPERATION. THE REMAINS S OF A. CLEANUP OPERATION. THTHE REMAINS OF A TRUCK AND SCATTERED. THTHE REMAINS OF A TRUCK AND SCATTERED DEBRIS. WHAT CAUSED. TRUCK AND SCATTERED DEBRIS. WHAT CAUSED THIS EXPLOSION? DEBRIS. WHAT CAUSESED THIS EXPLOSION? AND IS IT SAFE TO. THIS EXPLOSION? AND D IS IT SAFE TO OPERATE? AND IS IT SAFE TO OPERATE? >> FIRST, IT IS SAFE. OPERATE? >> FIRST, IT IS SAFE TO OPERATE N NOW. TO OPERATE NOW. WE DON'T KNOW THE ROOT CAUSE OF THE. WE DON'T KNOW THE ROOT CAUSE OF THE E ISSUE. D. ISSUE. ITIT WAS ISOLATED BETWEEN A COUPLE OF. IT WAS ISOLATED BETWEEN A COUPLE OF OUR BATTERIES. BETWEEN A COUPLE OF OUR BATTERIES. SO WE ARE.

SO WE ARE INVESTIGATING THAT. >> Reporter: THE. >> Reporter: THE EXPLOSION KILLING TWO PEPEOPLE, 39-YEAR-. TWO PEOPLE, 39-YEAR- OLD TIMOTHY QUINN, A FATHTHER WHO CAME FROM. OLD TIMOTHY QUQUINN, A FATHER WHO CAME FROM A STEEL MILL WORKING. FATHER WHO CAME FROM A STEEL MILL WORKING FAMILY. THE SECOND. FAMILY. THE SECOND PERSON KILLED HAS YET TO BE. PERSON KILLED HAS YET TO BE IDENTIFIED. YET TO BE IDENTIFIED. >> THEY ARE FAMILY. IDENTIFIED. . >> THEY ARE FAMILY. THAT IS WHAT WE ARE. >> THEY ARE FAMILY. THAT IS S WHAT WE ARE IN HERE. THAT IS WHAT WE ARE IN H HERE. AND IN AN INCIDENT. ININ HERE. AND IN AN INCIDENT LIKE THIS, WE BOND. AND ININ AN INCIDENT LIKE THIS, WE BOND TOGETHER. LIKE THIS, WE BONDND TOGETHER. >> WITH THAT, TOGETHER. >> WITH THAT, ADRIENNE BROADDUS. ADRIENNE BROADDUS JOINS US TONIGHT. PART OF THATAT FACTORY. PART OF THAT FACTORY BEHIND YOU STILL SHUT DOWN N ? BEHIND YOU STILL SHUT DOWN ? >> Reporter: TOM,

>> Reporter: TOM, THAT'S RIGHT. PART OF THE PLANT. PART OF THE PLANT REMAINS OFF-LINE OUT OF AN ABUNDANCE OF. OF AN ABUNDANCE OF CAUTION. THAT IS WHAT. THAT IS WHAT INVESTIGATORS ARE TELLING USUS. TELLING US. PLANT OFFICIALS ALSO SAY THEY HAVE.