Two workers were critically injured and two more were hurt when the huge main stage LED screen at this weekend's Ultra Music Festival in Miami toppled over on Thursday night.

According to the Miami Herald, rescue officials said the two men who suffered life-threatening injuries were trapped underneath the giant LED screen when it fell, with one possibly sustaining two broken legs. Two other workers were also hurt by falling equipment in the incident on the eve of the massive EDM gathering that is expected to bring 165,000 dance fans to the city's Bayfront Park for the 15th annual event. One was in stable condition at a local hospital and the other was treated on the scene.

The accident happened around 8 p.m. ET on the main stage at Ultra, which is slated to expand to two weekends for the first time in its history this year. It reportedly occurred when the screen was being hosted up into position over the main stage DJ booth. "Today (Thursday, March 14) as preparations were being made for this weekend's Ultra Music Festival, a section of an LED screen fell and injured two workers," read a statement from a publicist for the event. "Fire Rescue was on site so there was a rapid response. Festival organizers are working with, and supporting, authorities as they investigate the details behind the accident."

No ticketed patrons were on site during the incident. At press time an Ultra spokesperson could not be reached for comment on whether the accident would delay the planned 3 p.m. ET start of the festival.

Miami Fire Rescue spokesman Ignatius Carroll told the Herald that the fire marshal and investigators would return to the scene on Friday morning (March 15) to begin their investigation. Among the acts on the lineup for Ultra are: Snoop Lion, Afrojack, Avicii, Calvin Harris, David Guetta, Swedish House Mafia, Deadmau5, Boys Noize and dozens of others.