Indiana Investigating Ammonia Leak that Injured 4

State investigators will probe an explosion at a northern Indiana fertilizer plant that injured four people, including two who are in critical condition at a Fort Wayne hospital.

Indiana Occupational Safety and Health Administration spokeswoman Chetrice Mosley says investigators were headed Tuesday to T & T Fertilizer southwest of Goshen to investigate the accident.

Authorities say four workers of T & T Fertilizer and Southwest Welding in Goshen were injured when a tank exploded during welding Monday.

St. Joseph Hospital spokeswoman Shelly Lybarger says 24-year-old Adrian Martin and 16-year-old Anthony Rodes are in critical condition. A person answering the telephone at Southwest Welding identified them as employees.

The conditions of the other two workers were not available.

There was no answer at T & T Fertilizer on Tuesday.