CNN reported that hospitals had been told to expect "somewhere in the neighbourhood" of 100 people injured. A field triage centre had been set up.
Hospitals in the area have had "a steady flow" of people being admitted with orthopaedic injures and major blood loss.
Glenn A Robinson, the chief executive of Hillcrest Baptist Medical Center in Waco, told CNN that his hospital had received 66 injured people for treatment, including 38 who were seriously hurt.
He said the injuries included blast injuries, orthopedic injuries, large wounds and a lot of cuts. The hospital has set up a hotline for families of the victims to get information, he said.
