WOBURN — A host of emergency rescue crews responded to the Avalon Woburn apartment complex after a worker reportedly fell through a hole in a roof around 11 this morning and was very seriously injured.

According to sources, the unidentified victim, reportedly about 29 years of age, was seriously injured and in "traumatic cardiac arrest" when Woburn Fire Department rescue crews arrived.

He was rushed to Lahey Clinic in Burlington by Woburn and Action ambulance crews.

According to Fire Chief Paul Tortolano, the victim had fallen through a hole in the roof, apparently designed for some duct work or cables, and was not immediately noticed missing by employees who later went into the building and found the man on the ground.

Chief Tortolano said upon learning of the accident he immediately notified the federal Occupational Safety and Health Administration (OSHA), which will lead the investigation into the accident.

The Avalon Woburn apartment complex is located off Route 93 off West Street in Reading at the Wilmington line.

Some units are already being rented out while construction continues on the remaining buildings. The complex, when completed, will contain some 490 apartment units.

Efforts to send a reporter to the scene were blocked by security officials from the apartment complex.

Woburn Fire with Engine 4 as well as Rescue 1, responded along with Action Ambulance crews.