Railway sources said when the extra engine was being coupled to 6359 Ernakulam-Rajendra Nagar (Patna) Express at 1015 hours, it caused a severe jolt injuring 21 passengers.
The injured were immediately provided treatment at the railway hospital at Amla and one seriously injured was referred to the district hospital here. The bogey number 98785 was also damaged, Central Railway's Nagpur spokesman Suhas Lohkare said.
The train left for its onward journey after one and a half hours delay.
Extra engine driver Dhanraj and a pointsman were suspended and notices issued to Tigaon Station Master.
UNI XC-SP SY DS1520