HOMESTEAD, Fla. -- Three workers were shocked by a live power line while erecting a sign at a shopping center Monday.

It happened at 1801 N.E. Eighth St.

Miami-Dade fire-rescue Lt. Eddy Ballester said they were on a boom truck installing signs at a shopping center when they got too close to a high-tension power line and were shocked.

Ballester said the electric shock was so intense it caused a 20- to 30-foot portion of the ground to crack. It even flattened the tires of the truck.

All three people airlifted to Jackson Memorial Hospital in serious condition. A fourth person was treated at the scene.