The Ben Taub hospital was immediately placed on lockdown.
Patients and staff have been evacuated from the facility while it is being searched.
Houston police say a preliminary search of all six floors of the building has so far uncovered nothing.
However, officers say the operation is ongoing.
“It is important for people to realise that there were multiple reports from this location of shots being fired and a white male, unknown age, bald, being described as a suspect,” said a police spokesperson. (Euronews)
We are responding to reports of shots fired at Ben Taub Hospital; SWAT and PIO enroute #hounews— Houston Police (@houstonpolice) 21 febbraio 2017
Officers in the process of searching the hospital; no reports of injuries at this time #hounews— Houston Police (@houstonpolice) 21 febbraio 2017