Eight people are injured, and four critically, after a “humongous” explosion at a gas plant about 40 miles north of Orlando late Monday night. Gas tanks at the Blue Rhino plant began to explode about 11 p.m., sending a giant fireball into the sky and shaking people’s homes in towns as far as 10 miles away. Fifteen people were originally reported missing but have since been located, and the plant says all its employees are accounted for and alive. There were 53,000 20-pound propane tanks in the part of the plant where the explosion took place, and people nearby said they heard a string of booms. Officials said Tuesday that human error and equipment malfunction likely caused the blasts.